find the exact value

Question

find the exact value of:

cos(arcsin(-(√2)/2))

Answer 1

sin is negative in the 3rd and 4th quadrants

sin(225º)=-√2/2

sin(315º)=-√2/2

cos is negative in the 3rd quadrant and positive in the 4th quadrant

cos(225º)=-√2/2

cos(315º)=√2/2