Question

Write the given expression as an algebraic expression in x. cos(2 cos−1 x)

Answer 1

you will need the double angle identity

Answer 2

\[\cos(2a)=\cos^2(a)-\sin^2(a)\]
let a=arccos(x)
then cos(a)=x
draw a right triangle using the equation cos(a)=x
Then find any missing measurements by pythagorean theorem

Answer 3

I am unsure how to make the triangle