Hey guys, so I need help with some pre-calculus problems. Bear with me, it's a lot of problems, but I really need help, so without further ado, here they are: 
On problem 45, you have to find all solutions of the equation in the interval [0, 2π). This is the problem 
cos 4x (cos x-1) = 0 
On problem 47, you have to use inverse functions where needed to find all solutions of the equation in the interval [0, 2π). 
sin2x - 2 sin x = 0 
On problem 51 and 53, you have to find the exact value of the sine, cosine, and tangent of the angle by using a sum or difference formula. 
51) 285°= 315°-30° 
53) 25π/12 = 11π/6 + π/4 
On problem 69, you have to use double-angle formulas to verify the identity algebraically and use a graphing utility to confirm it graphically. 
sin 4x = 8 cos3x sin x - 4 cos x sin x 
On problem 79 and 81, you have to use the half-angle formulas to determine the exact values of the sine, cosine, and tangent of the angle. 
79) - 75° 
81) 19π/12 
On problem 83, you have to use half-angle formulas to simplify the expression 
- √1 + cos 10x /2 
That is all the problems I needed help on. Thanks for taking the time to read these and I hope you could help out in some way!