Question

sin^2 1^.+sin^2 2^.+sin^2 3^.+ sin^2 5^.+....sin^2 43^.+sin^2 45^.+....+sin^2 89^. =?​

Answer 1

Step-by-step explanation:

sin²1+sin²2+sin²3+.....….....sin²87+sin²88+sin²89

=sin²1+sin²2+sin²3+...…..+sin²(90-3)+sin²(90-2)+sin²(90-1)

=sin²1+sin²2+sin²3+........+cos²87+cos²88+cos²89

=(sin²1+cos²1)+(sin²2+cos²2)+(sin²3+cos²3)+.......…+(sin²45+cos²45)

=45