Question

Use a double-angle formula to rewrite the expression.14 cos2 x − 7

Answer 1

we have the expression

`\begin{gathered} 14cos^2x-7 \\ 7(2cos^2x-1) \end{gathered}`

Remember that

`cos(2x)=2cos^2x-1`

substitute in the given expression

`\begin{gathered} 7(2cos^(2)x-1) \\ 7(cos(2x)) \\ 7cos(2x) \end{gathered}`