tan(a+π/4)=2 = [1 + tana]/[1 - tana] ,解得tana = 1/31+3sina*cosa-2*cosa^2 = (3/2)·sin(2a) - cos(2a)sin(2a) = 2tana/[1 + (tana)^2] = 3/5cos(2a) = [1 - (tana)^2]/[1 + (tana)^2] = 4/5故:1+3sina*cosa-2...
tan(a+π/4)=2,则1+3sina*cosa-2*cosa^2=?
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