Gah: Trigonometry

I've been doing some trigonomtry homework and I've nearly got it done.  All I need done are these three problems... but I can't figure it out...

HAAAAAAAAAAALP!

I need to be able to solve the problems and understand them so working it out is appreciated.

1) 1+sin(theta)/cos(theta) + cos(theta)/1+sin(theta) = 2sec(theta)
2) sin(theta)/1-cot(theta) - cos(theta)/tan(theta)-1 = sin(theta) + cos(theta)
3) (3cos(theta) - 4sin(theta))(squared) + (4cos(theta) + 3cos(theta))(squared) = 25

>>9
Change one -24sin(θ)cos(θ) to +24sin(θ)cos(θ) in step 1. Expand.