Question

if a,b are supplementary angles, then cos²a + sin² b

Answer 1

Given that, a + b = 180
            ⇒  a = 180 - b
           or  Cosa = Cos(180 - b)
           ⇒  Cosa = -Cosb
           ⇒  Cos²a = Cos²b

Now,    cos²a + sin²b
                  = cos²b + sin²b    [Putting value form above]
                  = 1

Answer 2

Answer:

1 is the answer for this question