Question

Simplify $1-2{\sin }^2\theta -2{\cos }^2\theta$.

• A. $-2$
• B. $-1$
• C. $0$
• D. $1$

Answer 1

The correct option is B $-1$

We will use ${\sin }^2\theta +{\cos }^2\theta =1$ to simplify the given expression.

So, we have

$\begin{array}{cc}1-2{\sin }^2\theta -2{\cos }^2\theta & =1-2\left({\sin }^2\theta +{\cos }^2\theta \right)\\ & =1-2\left(1\right)\\ & =1-2\\ & =-1\end{array}$

Hence, option $B$ is correct.