From the top of a 7m high building, the angle of elevation of the top of a cable tower is 60° and the angle of depression of its foot is 45°. Determine the height of the tower.
Solution:
EC=DE+CD CD=AB=7 m BC=AD In △ABC, tan45°=AB/BC=CD/AD BC=7 × 1 m=AD=7 m AD=CD=7 m In △ADE, tan60°=DE/AD DE=7√3 m Height of tower=EC=DE+CD=(7√3+7) m=7(√3+1) m