化简sin210°tan(-120°)+cos(-240°)tan420°

化简sin210°tan(-120°)+cos(-240°)tan420° sin210°等于多少 化简：cos150°+sin210°+cos1470°+cos(-570°) sin120°、sin210°分别是多少? 求值：sin210°+cos120°-tan300°=? sin210°+sin220°+sin230°+sin240°+sin250°+sin260°+sin270°+sin280 sin25°+sin210°+sin215°+...+sin280°+sin285°＝? cos（-675°） sin330° tan135°-sin210° 求值 求sin 135°+cos平方 150°+2sin210°cos平方 225° cos330°+sin210°=?要过程~我没分了,帮帮忙!用分数表示! a=sin(cos210°)和b=sin(sin210°),a,b哪个大 化简：cos150+sin210+cos1470+cos(-570) 根号sin^2 150°+sin^2 35° +2sin210°+cos^2 325°根号sin^2 150°+sin^2 35° +2sin210°+cos^2 325° 根号下sin²150°+cos²35°+2sin210°cos²145° 等于? sin210°=sin(180°+30°)=-sin30°=-1/2为何这样分解计算 sin²150°+sin²135°+2sin210°+cos²225°在线等 sin²150°+sin²135°+2sin210°+cos²225°的值 如题 a=sin(cos210°)和b=sin(sin210°),a,b哪个大请说明为什么