Question

Find sin it cos8 it cos 8 = - 12 is in the third quadrant.04-12OBI08-1ORYReset Selection

Answer 1

Solution:

Given:

$cos\theta=-\frac{\sqrt{2}}{2}$$\begin{gathered} \theta=cos^{-1}(-\frac{\sqrt{2}}{2}) \\ \theta=135^0 \\ \\ In\text{ the third quadrant, } \\ \theta=180+45 \\ \theta=225^0 \end{gathered}$

Hence,

$sin225^0=-\frac{\sqrt{2}}{2}$

Therefore, the correct answer is OPTION A.