cos (-585°）怎么算还有sin（-495°

4个回答

cos(-585度)=cos(585度）=cos(225度）=-cos45度=-2开平方/2
cos(-3p-a)=cos(-p-a)=cos(p+a)=-cosa
sin(-a-4p)=sin（-a)=-sina
sin(-495度）=sin(-135度）=-sin135度=-sin45度=-2开平方/2
sin(-570度)=sin(-210度)=-sin210度=-sin(30度+180度）=sin30度=1/2

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