Question

Cos2 45+ cos2 135 + cos2 225 + cos2 315°​

Answer 1

Step-by-step explanation:

cos^2 45+cos^2(90+45)+cos^2(180+45)+cos^2(270+45)

=cos^2 45-sin^2 45-cos^2 45-sin^245

=(1/root2)^2+(-1/root2)^2+(-1/root2)^2+(-1/root2)^2

=1/2+1/2+1/2+1/2

=4/2

=2