展开 cos((3pi)/4-(5pi)/4)

解答

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cos (\frac{3 π}{4} - \frac{5 π}{4})

0

求解步骤

cos (\frac{3 π}{4} - \frac{5 π}{4})

化简

\frac{3 π}{4} - \frac{5 π}{4} : - \frac{π}{2}

= cos (- \frac{π}{2})

利用以下特性:

cos (- x) = cos (x)

cos (- \frac{π}{2}) = cos (\frac{π}{2})

= cos (\frac{π}{2})

使用以下普通恒等式:

cos (\frac{π}{2}) = 0

= 0

e x p an d sin^{3} (2 x) (5 x + 3)^{7}

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

e x p an d \frac{1}{( s - y ) ^{2}}

e x p an d (x - \frac{1}{2})^{2} - \frac{81}{4}

e x p an d \frac{( 5 a - 2 b ) ( 3 ab )}{2}