Question

Cum se mai poate scrie sin 3x(formula....)

Answer 1

sin(3x)=sin(x+2x)=sin(x)*cos(2x)+cos(x)*sin(2x)=sin(x)*[1-2sin²(x)]+cos(x)*2*cos(x)*sin(x)=sin(x)-2sin³(x)+2cos²(x)*sin(x)=sin(x)-2sin³(x)+2[1-sin²(x)]*sin(x)=sin(x)-2sin³(x)+2sin(x)-2sin³(x)=3sin(x)-4sin³(x).

Deci sin(3x)=3sin(x)-4sin³(x).

Green eyes.