1) Find the exact measures of sin2x, cos2x, and tan2x using the double angle formulas, that sinx = -12/13. Show all work.
2) Find the exact value of the trig function given that sinx = 12/13 and cosy = -4/5 and you are in Quadrant 2. Show all work.
3) Find all solutions of the equation cosx + sin2x = 0 in the interval [0, 2π). For this one, I changed sin2x to 2sinxcosx, then factored out a cosx, for it to be cosx(1 + 2sinx), but am unsure where to go from there.
Any help is appreciated!