化简cos(5/2π+α)

化简:cos(-π-α) 化简sin(α-5π)/cos(3π-α)×cos(π/2-α)/sin(α-3π)×cos(8π-α)/sin(-α- ①化简[sin(2π+α)*cos(7π-α)]/cos(-α)②已知cosθ=-3/5,θ∈(π/2,π),求sin( 化简{sin(π+α)^3cos(-α)cos(π+α)}/{tan(π+α)^3cos(-π-α)^2} (1+sinα+cosα)*[sin(α/2)-cos(α/2)]/√(2+2cosα)化简 （3/2*π 化简：[ cos(α-π/2)/sin(5π/2+α) ] ×sin(α-2π) × cos（2π-α） 化简cos(π/12-α)-根号3cos(5π/12+α) 化简：sinα-√3 cosα+2cos(α-π/3) 若cos(α-3π/2)=1/5,求-cosα的值. 化简cos（π/12）*cos（5π/12） cos(2π/3-α)能等于cosα? 化简:sin^2αcos^2β-cos^2αsin^2β+cos^2α-cos^2β具体步骤,