Question

The value of $\cos 1°·\cos 2°...\cos 100°$ is

• A. $-1$
• B. $0$
• C. $1$
• D. None of these

Answer 1

The correct option is B

$0$

Explanation of the correct option:

Find the value of the expression:

We know that,

$\cos 90°=0$

By substituting the value of $\cos 90°$ in the given expression, then we get,

$\begin{array}{rcl}& =& \cos 1°·\cos 2°·...\cos 90°·\cos 91°·....·\cos 100°\\ & =& \cos 1°·\cos 2°·...·\left(0\right)·\cos 91°·....·\cos 100°\\ & =& 0\end{array}$

Hence, the correct option is B.