Question

Evaluate $\left|\begin{array}{cc}\cos 15& \sin 15\\ \sin 75& \cos 75\end{array}\right|$

• A. 1
• B. 0
• C. 2
• D. 3

Answer 1

Answer: (B)

$\left|\begin{array}{cc}\cos 15& \sin 15\\ \sin 75& \cos 75\end{array}\right|$
$=\cos 15\cos 75-\sin 15\sin 75$
$=\cos (15+75)=\cos 90=0$