Question

Cos^2theta - Sin^2theta=?

Answer 1

Trigonometric Identities

Answer 2

start with
\[\cos(a+b)=cosa*cosb-sina*sinb\]

Answer 3

Welcome to Openstudy.

Answer 4

are u familiar with this formula?

Answer 5

I only have 5 possible answers also!
\[\left( \cos \theta -\sin \theta \right)^{2}\]

Answer 6

\[\cos(a+b)=cosa∗cosb−sina∗sinb\]
yeah in this indentity if u repalce b=a then u will get
\[\cos(a+a)=cosa*cosa-sina*sina \]
\[\cos(2a)=\cos^2(a)-\sin^2(a)\]
so \[\cos^2(\theta)-\sin^2(\theta)=\cos(2\theta)\]
ok????