已知sin(π/2+a)=-3/5 且 π/2

问题描述:

已知sin(π/2+a)=-3/5 且 π/2

数学人气:336 ℃时间:2020-05-28 09:34:08
优质解答
sin(π/2+a)= cos[π/2-(π/2+a)] = cos(-a) = cosa = -3/5
cos(π+a)= -cosa =-(-3/5) =3/5
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sin(π/2+a)= cos[π/2-(π/2+a)] = cos(-a) = cosa = -3/5
cos(π+a)= -cosa =-(-3/5) =3/5