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Home » A ladder long just reaches the top of a vertical wall. If the ladder makes an angle of with the wall then the height of the wall is (a) (b) (c) (d)
A ladder 15 \mathrm{~m} long just reaches the top of a vertical wall. If the ladder makes an angle of 60^{\circ} with the wall then the height of the wall is (a) 15 \sqrt{3} (b) \frac{15 \sqrt{3}}{2} (c) \frac{15}{2} (d) 15 \mathrm{~m}
CBSE | Class 10 | Maths | RS Aggarwal | Some Applications Of Trigonometry
A ladder 15 \mathrm{~m} long just reaches the top of a vertical wall. If the ladder makes an angle of 60^{\circ} with the wall then the height of the wall is (a) 15 \sqrt{3} (b) \frac{15 \sqrt{3}}{2} (c) \frac{15}{2} (d) 15 \mathrm{~m}

Let \mathrm{AB} be the wall and \mathrm{AC} be the ladder

\mathrm{AC}=15 \mathrm{~m} and \angle \mathrm{BAC}=60^{\circ}

\cos 60^{\circ}=\frac{\mathrm{AB}}{\mathrm{AC}}

\Rightarrow \frac{1}{2}=\frac{A B}{15}

\therefore \mathrm{AB}=\frac{15}{2} \mathrm{~m}

=> the correct answer is option (c).

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