展开 cos(2t)U(t-(5pi)/2)

解答

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cos (2 t) U (t - \frac{5 π}{2})

t U cos (2 t) - \frac{5 π U cos ( 2 t )}{2}

求解步骤

cos (2 t) U (t - \frac{5 π}{2})

= U cos (2 t) (t - \frac{5 π}{2})

使用分配律:

a (b - c) = ab - a c

a = cos (2 t) U, b = t, c = \frac{5 π}{2}

= cos (2 t) U t - cos (2 t) U \frac{5 π}{2}

= t U cos (2 t) - \frac{5 π}{2} U cos (2 t)

化简

t U cos (2 t) - \frac{5 π}{2} U cos (2 t) : t U cos (2 t) - \frac{5 π U cos ( 2 t )}{2}

= t U cos (2 t) - \frac{5 π U cos ( 2 t )}{2}

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