展开 (2-cos(θ))^2

解答

展开

(2 - cos (θ))^{2}

4 - 4 cos (θ) + cos^{2} (θ)

求解步骤

(2 - cos (θ))^{2}

使用完全平方公式:

(a - b)^{2} = a^{2} - 2 ab + b^{2}

(2 - cos (θ))^{2} = 2^{2} - 2 \cdot 2 cos (θ) + cos^{2} (θ)

= 2^{2} - 2 \cdot 2 cos (θ) + cos^{2} (θ)

化简

2^{2} - 2 \cdot 2 cos (θ) + cos^{2} (θ) : 4 - 4 cos (θ) + cos^{2} (θ)

= 4 - 4 cos (θ) + cos^{2} (θ)

s im pl i f y 15 (- \frac{1}{2 t ^{2}} + \frac{1}{2})

e x p an d \frac{2 ( sin ( 2 x ) + 1 )}{3 cos ^{2} ( 2 x )}

s im pl i f y (x - \frac{3}{2}) (x - \frac{1}{2})

e x p an d (15 + x) (\frac{15 + x}{2})^{2}

e x p an d + 10 y^{2} a t (2, 1, - 14)