Question

$\begin{vmatrix}cosx \ \ sinx\\ sinx \ \ cosx \end{vmatrix} =$

• A. 0
• B. cos2x
• C. 1
• D. sin2x

Answer 1

Answer:

B. cos2x

$\begin{vmatrix}cosx \ \ sinx\\ sinx \ \ cosx \end{vmatrix} =$

$=(cosx \times cosx)-(sinx \times sinx)$

$={cos}^2x- {sin}^2x = cos2x$