Question

in triangle ABC, angle C =90 degree, find cos(A+B)

Answer 1

as we know
A+B+C=180and as C =90
A+B=90
so Cos(A+B)=Cos90=0
hope it may help you

Answer 2

For, a triangle ABC with Angle C = 90 degrees, Cos (A+B) would be 0

1) Given, in Triangle ABC, Angle C = 90 degrees.

2) Also in a triangle, A+B+C = 180 degrees.

3) A+B = 180-90 degrees = 90 degrees.

4) Taking Cosine both sides, cos(A+B) = cos (90) =0.