How do you find an equivalent algebraic expression for the composition cos(arcsin(x))?

1 Answer
Dec 6, 2015

sqrt(1-x^2)1x2.

Explanation:

Since cos^2(x)=1-sin^2(x)cos2(x)=1sin2(x), you have that cos(x)=\pm\sqrt(1-sin^2(x))cos(x)=±1sin2(x). So, your expression becomes

sqrt(1-sin^2(arcsin(x))1sin2(arcsin(x))

And since sin(arcsin(x))=xsin(arcsin(x))=x, then sin^2(arcsin(x))=x^2sin2(arcsin(x))=x2.

So, your expression becomes sqrt(1-x^2)1x2.