# Math Help - Trig expression

1. ## Trig expression

Let x be in the 2nd quadrant such that sin(x) = a.

Evaluate the expression in terms of a

Cos^2(arcsin(a))

Any help?

2. $cos^2\theta=1-sin^2\theta$

Sooooooooo...

$cos^2(arcsin(a))=1-sin^2(arcsin(a))$

Should be solvable from there

Last hint: $sin(arcsin\theta)=\theta$