Practicing Success
A radio antenna stands on top of a building 300 m tall. At a point on the ground, the angle of elevation of bottom of antenna is 45° and the top of antenna is 60°. What is the height of the antenna? - |
217 m 215 m 219.6 m 150 m |
219.6 m |
height of building = BC m , height of antenna = AB m In triangle BCD tan 45° = \(\frac{BC}{CD}\) 1 = \(\frac{BC}{CD}\) As , BC = 300 m . so , BD is also 300 m in triangle ACD tan 60° = \(\frac{AC}{CD}\) \(\sqrt{3}\) = \(\frac{AC}{CD}\) \(\sqrt{3}\) = AC , CD = 300 So , AC = 300\(\sqrt{3}\) AB = AC - BC = 300\(\sqrt{3}\) - 300 = 300(1.732 - 1) = 300 x 0.732 = 219.6 m |