We have to prove that 2 sin −1 3 5 = tan −1 24 7 .
Consider sin −1 3 5 =x, then,
sinx= 3 5 cosx= 1− ( 3 5 ) 2 = 25−9 25 = 4 5
Another trigonometric function is,
tanx= sinx cosx = 3 5 4 5 = 3 4 x= tan −1 3 4
Substitute sin −1 3 5 = tan −1 3 4 to the left hand side of the given equation,
2 sin −1 3 5 =2 tan −1 3 4 = tan −1 ( 2( 3 4 ) 1− ( 3 4 ) 2 ) = tan −1 ( 3 2 7 16 ) = tan −1 ( 24 7 )
Hence, it is proved that 2 sin −1 3 5 = tan −1 24 7 .