Question:
Mark the tick against the correct answer in the following:
$\left|\begin{array}{cc}\cos 15^{\circ} & \sin 15^{\circ} \\ \sin 15^{\circ} & \cos 15^{\circ}\end{array}\right|=?$
A. 1
B. $\frac{1}{2}$
C. $\frac{\sqrt{3}}{2}$
D. none of these
Solution:
