Giải các phương trình sau :
a) \(3sin^2x-4sinxcosx+5cos^2x=2\)
b) \(25sin^2x+15sin2x+9cos^2=25\)
c) sinx + cosx =1
d) 3cos2x - 4sin2x =1
f) \(4sin^2x-6cos^2x=0\)
g) \(5sin2x-6cos^2x=13\)
h) \(sinx=\sqrt{3}cosx\)
i) \(sin^4x+cos^4\left(x+\frac{\pi}{4}\right)=\frac{1}{4}\)
j)\(tanx+2cotx-3=0\)
k) \(tan^25x=\frac{1}{3}\)
m) \(sin^4x-cos^4x=cosx-2\)