cho tanx= - \(\dfrac{2}{3}\) tính A = \(\dfrac{3sin^2x-cos^2x}{2sin^2x}\)

cho cotx = \(\dfrac{3}{5}\) tính A = \(\dfrac{sin^2x-5cos^2x}{2cos^2x}\)

cho tanx=1 tính A = \(\dfrac{3sin^2x-cos^2x}{2sin^2x}\)

Cho cotx = -2 tính A = \(\dfrac{3sinx-cosx}{2sinx-cosx}\)