Question

A girl is observing a ball from the balcony which is 30 metre above from the ground and the angle of depression of the ball is alpha such that sec 2 alpha equal to cos alpha. Find the distance of line of sight of the ball. ​

Answer 1

Distance of line of sight of the ball. ​ = 30√2 m

Step-by-step explanation:

Sinα = BC/AC

=> Sinα = 30/AC

=> AC = 30/Sinα

AC = distance of line of sight of the ball. ​

Sec2α  = Cosα

there seems some mistake in data

as Range of Cos is less than 1  ( only considering + ve values)

& Range of  Sec is more than 1 ( only considering + ve values)

only possible value of α = 0°  

Hence mistake in data

it should be

Secα  = Cosecα

=> α = 45°

Sin45° = 1/√2

AC = 30/(1 /√2) = 30√2 m

distance of line of sight of the ball. ​ = 30√2 m

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