Question

Question #628c9

Answer 1

We have that

#(1+cosA)(1-CosA)(1+Cot^2A)= (1-cos^2 A)*(1+cos^2 A/sin^2 A)= (sin^2 A)*((sin^2 A+cos^2 A)/(sin^2 A))= (sin^2 A)*(1/(sin^2 A))=1#

Footnote

We used the identities

1. `sin^2A+cos^2A=1`

2.`cotA=cosA/sinA`