hello, i am having problems with my homework, theres five problems i can not figure out, any help would be great,

1) cot x * sec x * sin x = 1

2) 2sec^2 y =1/(1 - sin y) + 1/(1 + sin y)

3) sec^2 a + csc^2 a = sec^2 a * csc^2 a

4) sin^4 β - cos^4 β = 1 - 2cos^2 β

5) cos Φ/(1 + sinΦ) + (1 + sin Φ)/cos Φ = 2sec Φ

HELP PLEASEE!!!!!!!!!!!