Alright...I need some help with an Algebra problem and 2 Trig. problems...

"Express in Simplest form:" X/4 -4/x / 1 -4/x

I wrote: (x/4 - 4/x / 1- 4/x) x

x^2/4x - 4 / 1-4

...I'm stuck from this point on.

"Solve the following Trig. equation."

5 cos^2 (theta) -1 = 3 (1 - cos^2 (theta))

I wrote: 5 cos^2 (theta) -1= 3 (1 - cos^2 (theta)

5 cos^2 (theta) -1= 3 - 3 cos^2 (theta)

5 cos^2 (theta)-1 = cos^2 (theta)

...and I'm stuck.

Sin^2 (theta) - 2 Sin (theta) = 3

...I wrote,WTF?...

Seriously...Is there some type of "trick" to solving trig. equations? I seem to be the only one in my class to be "not-getting" this! The teacher will not take the time to explain trig. equation-solving to me...because she says "you should know how to do these"...If you could please give reasoning in words to your work on solving these 2 trig. equations I would appreciate it!P.S. Thank you to all on this forum who have helped me so far in other problems, I appreciate it.