问几道三角函数题目(1)已知tana=12/5 求sina,cosa(2)已知tan/tan-1=-1,求下列各式的值①
问几道三角函数题目
(1)已知tana=12/5 求sina,cosa(2)已知tan/tan-1=-1,求下列各式的值①sina-3cosa/sina+cosa②sin^2(a)+sinacosa+2(3)已知sinaθ+cosθ=1/5,θ属于(0,π)求值①tanθ ②sinθ-cosθ ③sin^3(θ)+cos^3(θ)已知tanα=2,求下列各值①2sina-3cosa/4sina-9cosa②2sin^2(a)-3cos^2(a)/4sin^2(a)-9cos^2(a)③4sin^2(a)-3sinacosa-5cos^2(a)