Hello, I've got a few questions that I need help with. I'm not sure how to do these, and any help is appreciated!

1) Solve algebraically the equation √3tan2x = 1, for 0 <= x <= Pi.

2) By expanding cos(x+y) show that the exact value of cos(x+y) is 3/5, where sinx = 7/25, and cosx = 20/25.

3) Solve the equation sinx°cos20° - cosx°sin20° = 4/9 for 0 < x < 180.

Thanks in advance!