Maths

36. A tree breaks due to storm and the broken part bends so that the top of the tree touches the ground making an angle of 30{}^\circ with the ground. The distance from the foot of the tree to the point where the top touches the ground is 10meters. Find the height of the tree.

Let us consider AC be the height of the tree which is (x + h) m It is given that; the broken portion of the tree is making an angle of 30o with the ground. In the fig. In ΔBCD, we get tan$30{}^\circ...

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34. A vertical tower stands on a horizontal plane and is surmounted by a flag staff of height 7m. From a point on the plane, the angle of elevation of the bottom of flag staff is 30{}^\circand that of the top of the flag staff is 45{}^\circ.Find the height of the tower.

\ As per the given information in the question, The length of the flag staff $=7$m Angles of elevation of the top and bottom of the flag staff from point D is$45{}^\circ $ and $30{}^\circ...

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33. A man sitting at a height of 20m on a tall tree on a small island in the middle of a river observes two poles directly opposite to each other on the two banks of the river and in line with foot of tree. If the angles of depression of the feet of the poles from a point at which the man is sitting on the tree on either side of the river are 60{}^\circ and 30{}^\circ respectively. Find the width of the river.

From the given information we can say that, Assume width of river =PQ=(x+y)m Height of tree will be (AB) $=20$m Thus, in ΔABP tan$60{}^\circ $=AB/ BP $\sqrt{3}=20/x$ $x=20\sqrt{3}m$ In ΔABQ, tan...

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32. Two poles of equal heights are standing opposite to each other on either side of the road which is 80 m wide. From a point between them on the road the angles of elevation of the top of the poles are 60{}^\circand 30{}^\circ respectively. Find the height of the poles and the distances of the point from the poles.

According to the question it is given that, Distance between the poles $=80$m=BD Assume the point of observation of the angles be O. The angles of elevation to the top of the points is $60{}^\circ...

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31. From a point on a bridge across a river the angle of depression of the banks on opposite side of the river are 30{}^\circ and 45{}^\circ respectively. If the bridge is at the height of 30m from the banks, find the width of the river.

As per the question it is given that, The bridge is at a height of $30$m from the banks. Assume, A and B represent the points on the bank on opposite sides of the river. And, AB is the width of the...

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30. The angle of elevation of the top of the building from the foot of the tower is 30{}^\circ and the angle of the top of the tower from the foot of the building is 60{}^\circ. If the tower is 50m high, find the height of the building.

Let us consider AB is the building and CD is the tower. As per the question we can see that, The angle of elevation of the top of the building from the foot of the tower is $30{}^\circ $. Now, the...

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29. As observed from the top of a 75 m tall lighthouse, the angles of depression of two ships are 30{}^\circ and 45{}^\circ. If one ship is exactly behind the other on the same side of the lighthouse, find the distance between the two ships.

As per the given information in the question we can say that, Height of the lighthouse $=75m$ = ‘h’ m = AB Angle of depression of ship 1, $\alpha =30{}^\circ $ Angle of depression of bottom of the...

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27. A T.V. tower stands vertically on a bank of a river of a river. From a point on the other bank directly opposite the tower, the angle of elevation of the top of the tower is 60{}^\circ. From a point 20m away this point on the same bank, the angle of elevation of the top of the tower is 30{}^\circ. Find the height of the tower and the width of the river.

Assume AB be the T.V tower of height ‘h’ m on the bank of river and ‘D’ be the point on the opposite side of the river. An angle of elevation at the top of the tower is $30{}^\circ $ Let us consider...

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26. A statue 1.6 m tall stands on the top of a pedestal. From a point on the ground, angle of elevation of the top of the statue is 60{}^\circ and from the same point the angle of elevation of the top of the pedestal is 45{}^\circ. Find the height of the pedestal.

Consider the AB as the statue, BC be the pedestal and D be the point on ground from where elevation angles are measured. As per the question it is given that, Angle of elevation of the top of statue...

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A 1.5m tall boy is standing at some distance from a 30m tall building. The angle of elevation from his eyes to the top of the building increases from {{30}^{\circ }} to {{60}^{\circ }} as he walks towards the building. Find the distance he walked towards the building.

As per the question it is given that, The height of the tall boy (AS) $=1.5m$ The length of the building (PQ) $=30m$ Assume the initial position of the boy be S. And, then he walks towards the...

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From a point P on the ground the angle of elevation of a 10m tall building is {{30}^{\circ }}. A flag is hoisted at the top of the building and the angle of elevation of the top of the flag staff from P is {{45}^{\circ }}. Find the length of the flag staff and the distance of the building from the point P.

Consider the height of flag-staff(AB) $=hm$ Then, the distance $PQ=xm$ It is  given in the question that, Angle of elevation of top of the building $={{30}^{\circ }}$ Angle of elevation of top of...

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A tree breaks due to storm and the broken part bends so that the top of the tree touches the ground making an angle of {{30}^{\circ }} with the ground. The distance between the foot of the tree to the point where the top touches the ground is 8m. Find the height of the tree.

Assume initial height of the tree be AC. Then, due to storm the tree is broken at B. Consider bent portion of the tree be $AB=xm$ and the remaining portion $BC=hm$ Thus, the height of the tree...

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On a horizontal plane there is a vertical tower with a flag pole on the top of the tower. At a point 9m away from the foot of the tower the angle of elevation of the top and bottom of the flag pole are {{60}^{\circ }} and {{30}^{\circ }} respectively. Find the height of the tower and the flag pole mounted on it.

Consider the BC be the tower and AB be the flag pole on the tower Distance of the point of observation from foot of the tower $DC=9m$ Angle of elevation of top of flag pole is ${{60}^{\circ }}$...

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From the top of a building 15m high the angle of elevation of the top of tower is found to be {{30}^{\circ }}. From the bottom of the same building, the angle of elevation of the top of the tower is found to be {{60}^{\circ }}. Find the height of the tower and the distance between the tower and the building.

As per the question it is given that, The height of the building $=15m$ The angle of elevation from the top of the building to top of the tower $={{30}^{\circ }}$ The angle of elevation from the...

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The angle of elevation of the top of a tower from a point A on the ground is {{30}^{\circ }}. On moving a distance of 20 meters towards the foot of the tower to a point B the angle of elevation increases to {{60}^{\circ }}. Find the height of the tower and the distance of the tower from the point A.

According to the question it is given that, Angle of elevation of top of the tower from point A, $\alpha ={{30}^{\circ }}$ Angle of elevation of top of tower from point B, $\beta ={{60}^{\circ }}$...

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The angle of elevation of the top of a tower as observed from a point in a horizontal plane through the foot of the tower is{{32}^{\circ }}. When the observer moves towards the tower a distance of 100m, he finds the angle of elevation of the top to be {{63}^{\circ }}. Find the height of the tower and the distance of the first position from the tower. [Take \tan {{32}^{\circ }}=0.6248 and \tan {{63}^{\circ }}=1.9626]

Assume the height of the tower $=hm$ Then the distance $BC=xm$ Now, from the fig. In $\vartriangle ABC$ $\tan {{63}^{\circ }}=AB/BC$ $1.9626=h/x$ $x=h/1.9626$ $x=0.5095h....(i)$ Next, in...

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The angle of elevation of a tower from a point on the same level as the foot of the tower is {{30}^{\circ }}. On advancing 150 meters towards the foot of the tower, the angle of elevation of the tower becomes {{60}^{\circ }}. Show that the height of the tower is 129.9 meters.

As per the question it is given that, The angle of elevation of top tower from first point D, $\alpha ={{30}^{\circ }}$ On advancing through D to C by $150m$, then $CD=150m$ Angle of elevation of...

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On the same side of a tower, two objects are located. When observed from the top of the tower, their angles of depression are {{45}^{\circ }} and {{60}^{\circ }}. If the height of the tower is 150 m, find the distance between the objects.

It is given in the question that, The height of the tower (AB) $=150m$ Angles of depressions of the two objects are ${{45}^{\circ }}$ and ${{60}^{\circ }}$. In $\vartriangle ABD$ $\tan {{45}^{\circ...

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A parachute is descending vertically and makes angles of elevation of {{45}^{\circ }} and {{60}^{\circ }} at two observing points 100 m apart from each other on the left side of himself. Find the maximum height from which he falls and the distance of point where he falls on the ground from the just observation point.

Assume  parachute at highest point A and assume C and D be points which are $100m$ apart on ground where from then $CD=100m$ Angle of elevation from point $D={{45}^{\circ }}=\alpha $ Angle of...

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A vertical tower stands on a horizontal plane and is surmounted by a vertical flag staff of height 5 meters. At a point on the plane, the angles of elevation of the bottom and the top of the flag staff are respectively {{30}^{\circ }} and {{60}^{\circ }}. Find the height of the tower.

As per the question it is given that, Height of the flag staff $=5m=AB$ Angle of elevation of the top of flag staff $={{60}^{\circ }}$ Angle of elevation of the bottom of the flagstaff...

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A vertical tower stands on a horizontal place and is surmounted by a vertical flag staff. At a point on the plane 70 meters away from the tower, an observer notices that the angles of elevation of the top and bottom of the flag-staff are respectively {{60}^{\circ }} and {{45}^{\circ }}. Find the height of the flag staff and that of the tower.

As per the question it is given that, A vertical tower is surmounted by flag staff. Distance between observer and the tower $=70m=DC$ Angle of elevation of bottom of the flag staff $={{45}^{\circ...

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An electric pole is 10m high. A steel wire tied to top of the pole is affixed at a point on the ground to keep the pole up right. If the wire makes an angle of {{45}^{\circ }} with the horizontal through the foot of the pole, find the length of the wire.

As per the question it is given, Height of the electric pole $=10m=AB$ The angle made by steel wire with ground (horizontal) $\theta ={{45}^{\circ }}$ Assume length of wire $=L=AC$ Thus, from the...

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A ladder is placed along a wall of a house such that its upper end is touching the top of the wall. The foot of the ladder is 2m away from the wall and the ladder is making an angle of {{60}^{\circ }} with the level of the ground. Determine the height of the wall.

As per the question, Distance between the wall and the foot of the ladder $=2m=BC$ Angle made by ladder with ground $\left( \theta  \right)={{60}^{\circ }}$ Height of the wall (H) $=AB$ Then, the...

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The square ABCD is divided into five equal parts, all having same area. The central part is circular and the lines AE, GC, BF and HD lie along the diagonals AC and BD of the square. If AB=22cm, find: (i) the circumference of the central part. (ii) the perimeter of the part ABEF.

According to the question, Side of the square $=22cm=AB$ Assume the radius of the center part be r cm. Now, area of the circle $=1/5\times $ area of the square $=\pi {{r}^{2}}=1/5\times {{22}^{2}}$...

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From each of the two opposite corners of a square of side 8cm, a quadrant of a circle of radius 1.4cm is cut. Another circle of radius 4.2cm is also cut from the center as shown in Fig. Find the area of the remaining (shaded) portion of the square. (Use \pi =22/7)

According to the question, Side of the square $=8cm$ Radius of circle $=4.2cm$ Radius of the quadrant $=1.4cm$ Therefore, Area of the shaded potion $=$ Area of square $–$ Area of circle $-2\times $...

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The inner perimeter of a running track (show in Fig.) is 400m. The length of each of the straight portion is 90 m and the ends are semi-circles. If the track is everywhere 14m wide, find the area of the track. Also, find the length of the outer running track

Assume radius of the inner semi-circle $=r$ And that of the outer semi-circle $=R$ As per the question it is given that, Length of the straight portion $=90m$ Width of the track $=14m$ The inner...

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A cylindrical vessel of diameter 14cm and height 42cm is fixed symmetrically inside a similar vessel of diameter 16cm and height of 42cm. The total space between the two vessels is filled with cork dust for heat insulation purposes. How many cubic cms of the cork dust will be required?

According to the question it is given that, Depth of the cylindrical vessel = Height of the cylindrical vessel $=h=42cm$ (common for both) Inner diameter of the cylindrical vessel $=14cm$ Thus, the...

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A vessel is a hollow cylinder fitted with a hemispherical bottom of the same base. The depth of the cylinder is 14/3 and the diameter of the hemisphere is 3.5m. Calculate the volume and the internal surface area of the solid.

As per the question it is given that, Diameter of the hemisphere $=3.5m$ Thus, the radius of the hemisphere (r) $=1.75m$ Height of the cylinder (h) $=14/3m$ We all know that, volume of the Cylinder...

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Consider a cylindrical tub having radius as 5cm and its length 9.8cm. It is full of water. A solid in the form of a right circular cone mounted on a hemisphere is immersed in tub. If the radius of the hemisphere is 3.5cm and the height of the cone outside the hemisphere is 5cm, find the volume of water left in the tub.

According  to the question we have, The radius of the Cylindrical tub (r) $=5cm$ Height of the Cylindrical tub (H) $=9.8cm$ Height of the cone outside the hemisphere (h) $=5cm$ Radius of the...

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A toy is in the shape of a right circular cylinder with a hemisphere on one end and a cone on the other. The radius and height of the cylindrical parts are 5cm and 13cm, respectively. The radii of the hemispherical and conical parts are the same as that of the cylindrical part. Find the surface area of the toy if the total height of the toy is 30cm.

It is given in the question that, Height of the Cylindrical portion (H) $=13cm$ Radius of the Cylindrical portion (r) $=5cm$ Height of the whole solid $=30cm$ Now, The curved surface area of the...

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A solid is in the form of a right circular cylinder, with a hemisphere at one end and a cone at the other end. The radius of the common base is 3.5cm and the height of the cylindrical and conical portions are 10cm and 6cm, respectively. Find the total surface area of the solid. (Use \pi =22/7).

According to the question, Radius of the common base (r) $=3.5cm$ Height of the cylindrical part (h) $=10cm$ Height of the conical part (H) $=6cm$ Assume, ‘l’ be the slant height of the cone Now, we...

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A rocket is in the form of a circular cylinder closed at the lower end with a cone of the same radius attached to the top. The cylinder is of radius 2.5m and height 21m and the cone has the slant height 8m. Calculate the total surface area and the volume of the rocket.

According to the question it is given that, Radius of the cylindrical portion of the rocket (R) $=2.5m$ Height of the cylindrical portion of the rocket (H) $=21m$ Slant Height of the Conical surface...

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A tent is in the form of a right circular cylinder surmounted by a cone. The diameter of cylinder is 24m. The height of the cylindrical portion is 11m while the vertex of the cone is 16m above the ground. Find the area of canvas required for the tent.

As per the question, The diameter of the cylinder (also the same for cone) $=24m$. Thus, its radius (R) $=24/2=12m$ The height of the cylindrical part $\left( {{H}_{1}} \right)=11m$ Now, Height of...

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The probability that a student will pass the final examination in both English and Hindi is 0.5 and the probability of passing neither is 0.1. If the probability of passing the English examination is 0.75. What is the probability of passing the Hindi examination?

Let ‘E’ denotes the event that student passes in English examination. And ‘H’ be the event that student passes in Hindi exam. It is given that, P (E) = 0.75 P (passing both) = P (E ∩ H) = 0.5 P...

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A bucket is in the form of a frustum of a cone of height 30cm with radii of its lower and upper ends as 10cmand 20cm respectively. Find the capacity and surface area of the bucket. Also, find the cost of milk which can completely fill the container, at the rate of Rs.25 per litre.

Let us assume  R and r be the radii of the top and base of the bucket respectively, Let us assume h be its height of the bucket. Then, according to the question we have $R=20cm$, $r=10cm$, $h=30cm$...

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A milk container of height 16cm is made of metal sheet in the form of frustum of a cone with radii of its lower and upper ends as 8cm and 20cm respectively. Find the cost of milk at the rate of Rs.44 per liter which the container can hold.

As per the given information, A milk container in a form of frustum of a cone with, Radius of the lower end $\left( {{r}_{1}} \right)=8cm$ And radius of the upper end $\left( {{r}_{2}} \right)=20cm$...

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