展开 cos(3(pi-θ))

解答

展开

cos (3 (π - θ))

- cos (3 θ)

求解步骤

cos (3 (π - θ))

乘开

3 (π - θ) : 3 π - 3 θ

= cos (3 π - 3 θ)

使用三角恒等式改写

= - cos (3 θ)

e x p an d \frac{ln ( n ( n + 1 ) )}{n + 1}

e x p an d x (x^{6} - 16 x^{4} = 0)

e x p an d \frac{x + 2}{x ^{2} ( x + 1 )}

e x p an d \frac{( 4 x + 8 )}{( ( x ^{2} - 1 ) ^{2} )}

e x p an d (w (z) = 2, - 4 i) (z = 1 + i)