Question

Using trigonometric identities, transform the left side of the equation into the right side:
(1+cos(x))(1-cos(x)) = sin^2(x)

Answer 1

Expand the left hand side.

Answer 2

Multiply it out.

Answer 3

Do you know how to multiply them?

Answer 4

I used the FOIL method and got
cos^4(x) = sin^2(x).

Answer 5

You did not foil responsibly.

Answer 6

\[\begin{split}
(1+\cos(x))(1-\cos(x))
&=(1-\cos(x))+\cos(x)(1-\cos(x)) \\
&=1-\cos(x)+\cos(x)-\cos(x)\cos(x) \\
&=1-\cos^2(x)

\end{split}
\]