化简:[sin(π+3α)cos(-α+3π)sin(α-3π/2)cos(11π/2-α)]÷[cos(3α+9π/2)sin(-α-π)化简:[sin(π+3α)cos(-α+3π)sin(α-3π/2)cos(11π/2-α)] ÷ [cos(3α+9π/2)sin(-α-π)tan(-π+α)tan(π/2-α)]
问题描述:
化简:[sin(π+3α)cos(-α+3π)sin(α-3π/2)cos(11π/2-α)]÷[cos(3α+9π/2)sin(-α-π)
化简:[sin(π+3α)cos(-α+3π)sin(α-3π/2)cos(11π/2-α)] ÷ [cos(3α+9π/2)sin(-α-π)tan(-π+α)tan(π/2-α)]
答
[sin(π+3α)cos(-α+3π)sin(α-3π/2)cos(11π/2-α)] ÷ [cos(3α+9π/2)sin(-α-π)tan(-π+α)tan(π/2-α)]
=[-sin3α(-cosα)cosα(-sinα)] ÷ [(-sin3α)sinαtanαcotα)]
=(-sin3αcos²αsinα) ÷ (-sin3αsinα)
=cos²α