Question

resolver: 1/1- cos A + 1/ 1+ cosA =

Answer 1

1/(1-cosA) +1/(1+cosA)=
((1+cosA)+(1-cosA))/(1-cos²A)
como:
sen²A+cos²A=1
sen²A=1-cos²A

2/sen²A
2(csc²A)