Prove the following trigonometric identities:
1+sin θcos θ+cos θ1+sin θ=2 sec θ
Prove the following
1.(1−sin2A)sec2A=1
2.sec4θ−sec2θ=tan4θ+tan2
3.(secθ−tanθ)2=1−sinθ1+sinθ
4.tanθ+secθ−1tanθ−secθ+=1+sinθcosθ