Question

(1+cosA)(1-cosA)=3/4, find cos A

Answer 1

(1+cosA)(1-cosA)=3/4

(1-cos^2A)=3/4

1-3/4=cos^2A

4-3/4=cos^2A

1/4=cos^2A

cosA=√1/4

cosA=1/2

cosA=cos60°

A=60°