Use a graphing calculator to make a conjecture as to whether each equation is an identity.
-$\cos 2 x = 2 \cos ^ { 2 } x - 1$
A) Identity
B) Not an Identity

Question

Quizplus · Accepted Answer

The equation $\cos 2x = 2\cos^2x - 1$ is a well-known trigonometric identity, which can be verified using the double-angle formula for cosine. Graphing both sides of the equation on a calculator will show that they are identical for all values of $x$, confirming it as an identity.

Use a Graphing Calculator to Make a Conjecture as to Whether