已知sin(π/6+a)=3/4,求cos(π/3-a)的值

如题所述

cos(π/3-a)
=cos(a-π/3)
=cos[(a+π/6)-π/2]
=sin(a+π/6)
=3/4
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第1个回答  2017-06-14
sin(π/6+A)=3/4
cos[π/2 -(π/6+A)] =3/4
cos(π/3 -A) =3/4