
Trig/Proving Identities
I'm completely stumped. were supposed to prove the equations true. if you could help me that would be great!
3.) sec^2(θ)sec^2(θ)sin^2(θ)=1
4.) sec^2(θ)cot^2(θ)1=cot^2(θ)
5.) 1/sec(θ)cos(θ)=cot(θ)csc(θ)
6.) sec^2(θ)+csc^2(θ)=csc^2(θ)sec^2(θ)
7.) [1/sin(θ)+1]  [1/sin(θ)1]=2sec^2(θ)
8.) [sin(θ)tan(θ]/[1cos(θ)]=sec(θ)=1

#1: It often helps to rewrite it in terms to sine and cosine.
$\displaystyle sec^{2}(x)sec^{2}(x)sin^{2}(x)$
$\displaystyle =\frac{1}{cos^{2}(x)}\frac{sin^{2}(x)}{cos^{2}(x)}$
$\displaystyle =\frac{1sin^{2}(x)}{cos^{2}(x)}$
$\displaystyle =\frac{cos^{2}(x)}{cos^{2}(x)}=1$