An observer stands away from the foot of a vertical flag-staff

MATHEMATICS · Multi-part · CBSE · Mathematics · Applications of Trigonometry · Applications of Trigonometry

Problem

An observer stands

20\,\text{m}

away from the foot of a vertical flag-staff. The angle of elevation of the top of the flag-staff is

\theta

, where

\sin\theta = \dfrac{12}{13}

. (i) Find

\cos\theta

. (ii) Calculate the height of the flag-staff, correct to one decimal place.