Question

The value of $\cos 1^{\circ }\cdot \cos 2^{\circ }\cdot \cos 3^{\circ }\cdots \cos {180}^{\circ }$ is

• A. $1$
• B. $\sqrt{2}$
• C. $0$
• D. $-1$

Answer 1

The correct option is C $0$

$\cos 1^{\circ }\cdot \cos 2^{\circ }\cdot \cos 3^{\circ }\cdots \cos {180}^{\circ }$
$=\cos 1^{\circ }\cdot \cos 2^{\circ }\cdot \cos 3^{\circ }\cdots \cos {90}^{\circ }\cdots \cos {180}^{\circ }$
$=0(\because \cos {90}^{\circ }=0)$