Question

`cos(2sin^-1  3/4+cos^-1  3/4)=` ______.

Options

• `3/4`

• does not exist

• `-3/4`

• `3/5`

Answer 1

`cos(2sin^-1  3/4 +cos^-1  3/4)= underline(-3/4)` .

Explanation:

`cos(2sin^-1  3/4+cos^-1  3/4)`

`=cos (sin^-1  3/4 +sin^-1  3/4+cos^-1  3/4)`

`=cos(pi/4+sin^-1  3/4)`

`= -cos(cos^-1  3/4)`

`=-3/4`