Answer: If a perpendicular is drawn from the vertex of the right angle of a right triangle to the hypotenuse then the triangles on the both sides of the...
Two chords AB and CD of a circle intersect at a point P outside the circle. Prove that: (i) ∆ PAC ~ ∆ PDB (ii) PA. PB = PC.PD
Answer: Given, AB and CD are two chords ∠???????????? + ∠???????????? = 180o …(1) ∠???????????? + ∠???????????? = 180p …(2) Using (1) and (2), ∠???????????? = ∠???????????? ∠???? = ∠A...
In a circle, two chords AB and CD intersect at a point P inside the circle. Prove that (a) ∆PAC ~ ∆PDB (b) PA. PB = PC. PD
Answer: Given, AB and CD are two chords In ∆ PAC and ∆ PDB ∠???????????? = ∠???????????? ∠???????????? = ∠???????????? By ???????? ????????????????????????????????????????...
ABCD is a quadrilateral in which AD = BC. If P, Q, R, S be the midpoints of AB, AC, CD and BD respectively, show that PQRS is a rhombus.
Answer: In ∆ ABC, P and Q are mid points of AB and AC respectively. So, PQ || BC, and PQ = $\begin{array}{l} \frac{{1}}{{2}} \end{array}$ ???????? …(1) Similarly, in...
In the given figure, ∠1 = ∠2 and . Prove that ∆ ACB ~ ∆ DCE.
Answer: Given, $\begin{array}{l} \frac{{AC}}{{BD}} = \frac{CB}{CE}\\ \frac{{AC}}{{CB}} = \frac{BD}{CE}\\ \frac{{AC}}{{CB}} = \frac{CD}{CE}\\ \end{array}$ ∠1 = ∠2 ∠???????????? =...
In an isosceles ∆ABC, the base AB is produced both ways in P and Q such that AP × BQ = AC2. Prove that ∆APC~∆BCQ.
Answer: Given. ∆ABC is an isosceles triangle. CA = CB ∠???????????? = ∠???????????? 180o − ∠???????????? = 180o − ∠???????????? ∠???????????? = ∠???????????? AP × BQ = ????????2...
A vertical pole of length 7.5cm casts a shadow 5m long on the ground and at the same time a tower casts a shadow 24m long. Find the height of the tower.
Answer: Let AB be the vertical stick and BC be its shadow. AB = 7.5 m, BC = 5 m Let PQ be the tower and QR be its shadow. QR = 24 m Let the length of PQ be x m. In ∆ ABC...
In the given figure, DB⊥BC, DE⊥AB and AC⊥BC. Prove that
Answer: In ∆BED and ∆ACB, ∠???????????? = ∠???????????? = 90o ∵ ∠???? + ∠???? = 180o ∴ BD || AC ∠???????????? = ∠???????????? By AA similarity theorem, ∆ BED ~ ∆ ACB $\begin{array}{l}...
ABCD is parallelogram and E is a point on BC. If the diagonal BD intersects AE at F, prove that AF × FB = EF × FD.
Answer: Given, ∠???????????? = ∠???????????? ∵ DA || BC ∴ ∠???????????? = ∠???????????? ∆ DAF ~ ∆ BEF $\begin{array}{l} \frac{{AF}}{{EF}} = \frac{FD}{FB}\\ \end{array}$...
P and Q are points on the sides AB and AC respectively of a ∆ABC. If AP = 2cm, PB = 4cm, AQ = 3cm and QC = 6cm, show that BC = 3PQ
Answer: Given, $\begin{array}{l} \frac{{AP}}{{AB}} = \frac{2}{6} = \frac{1}{3}\\ \frac{{AQ}}{{AC}} = \frac{3}{9} = \frac{1}{3}\\ \\ \frac{{AP}}{{AB}} = \frac{{AQ}}{{AC}} \end{array}$ By AA...
In the given figure, ∠ABC = 90o and BD⊥AC. If BD = 8cm, AD = 4cm, find CD.
Answer: Given, ABC is a right-angled triangle BD is the altitude drawn from the right angle to the hypotenuse. In ∆ DBA and ∆ DCB, ∠???????????? = ∠????????????...
In the given figure, ∠ABC = 90o and BD⊥AC. If AB = 5.7cm, BD = 3.8cm and CD = 5.4cm, find BC.
Answer: Given, ABC is a right-angled triangle and BD is the altitude drawn from the right angle to the hypotenuse. In ∆ BDC and ∆ ABC, ∠???????????? = ∠???????????? = 90o ∠???? = ∠????...
In the given figure, ∠CAB = 90o and AD⊥BC. Show that ∆BDA ~ ∆BAC. If AC = 75cm, AB = 1m and BC = 1.25m, find AD.
Answer: In ∆ BDA and ∆ BAC, ∠???????????? = ∠???????????? = 90o ∠???????????? = ∠???????????? By AA similarity theorem, ∆ BDA - ∆ BAC $\begin{array}{l} \frac{{AD}}{{AC}} =...
The corresponding sides of two similar triangles ABC and DEF are BC = 9.1cm and EF = 6.5cm. If the perimeter of ∆DEF is 25cm, find the perimeter of ∆ABC
Answer: Given, ∆ ABC - ∆ DEF Their corresponding sides will be proportional. Ratio of the perimeters of similar triangles is same as the ratio of their corresponding sides. $\begin{array}{l}...
The perimeter of two similar triangles ABC and PQR are 32cm and 24cm respectively. If PQ = 12cm, find AB.
Answer: Given, Triangles ABC and PQR are similar. $\begin{array}{l} \frac{{Perimeter( ABC)}}{{ Perimeter( PQR)}} = \frac{{AB}}{{PQ}}\\ \end{array}$ $\begin{array}{l} \frac{{32}}{{24}} =...
In the given figure, if ∠ADE = ∠B, show that ∆ADE ~ ∆ABC. If AD = 3.8cm, AE = 3.6cm, BE = 2.1cm and BC = 4.2cm, find DE.
Answer: Given, ∠???????????? = ∠???????????? ???????????? ∠???? = ∠???? Let DE be X cm By AA similarity theorem, ∆ ADE - ∆ ABC $\begin{array}{l} \frac{{AD}}{{AB}} =...
In the given figure, ∆OAB ~ ∆OCD. If AB = 8cm, BO = 6.4cm, OC = 3.5cm and CD = 5cm, find (i) OA (ii) DO
Answers: (i) Let OA be X cm. ∵ ∆ OAB - ∆ OCD $\begin{array}{l} \frac{{OA}}{{OC}} = \frac{{AB}}{{CD}}\\ \end{array}$ $\begin{array}{l} \frac{{x}}{{3.5}} =...
In the given figure, ∆ODC~∆OBA, ∠BOC = 115o and ∠CDO = 70 o. Find (i) ∠OAB (ii) ∠OBA.
Answers: (i) Given, ∆ ODC - ∆ OBA ∠???????????? = ∠???????????? = 45 o (ii) Given, ∆ ODC- ∆ OBA ∠???????????? = ∠???????????? = 70...
In the given figure, ∆ODC~∆OBA, ∠BOC = 115o and ∠CDO = 70o. Find (i) ∠DCO (ii) ∠DCO
Answers: (i) Given, DB is a straight line. ∠???????????? + ∠???????????? = 180o ∠???????????? = 180o − 115o = 65o (ii) In ∆ DOC, ∠???????????? +...
In each of the given pairs of triangles, find which pair of triangles are similar. State the similarity criterion and write the similarity relation in symbolic form:
Answer: In ∆ ABC ∠A + ∠???? + ∠???? = 1800 (Angle Sum Property) 800 + ∠???? + 700 = 180o ∠???? = 30o ∠???? = ∠???? ???????????? ∠???? = ∠???? By AA similarity, ∆ ABC - ∆ MNR...
In each of the given pairs of triangles, find which pair of triangles are similar. State the similarity criterion and write the similarity relation in symbolic form:
Answers: (iii) Given, $\begin{array}{l} \frac{{CA}}{{QR}} = \frac{{8}}{{6}}\\ \end{array}$ $\begin{array}{l} \frac{{CA}}{{QR}} =...
In each of the given pairs of triangles, find which pair of triangles are similar. State the similarity criterion and write the similarity relation in symbolic form:
Answers: (i) Given, ∠BAC = ∠PQR = 50o ∠ABC = ∠QPR = 60 o ∠ACB = ∠PRQ = 70 o By AAA similarity theorem, ∆ ABC – QPR (ii) Given, $\begin{array}{l}...