cos(pai/4-a)=3/5,sin(5pai/4+b)=-12/13,a属于大于45度小于135度,b属于大于0度小于45度求sin(a+b)

cos (a+4pai)cos ^2(a+pai)sin^2(a+3pai)/ sin(a-4pai)sin(5pai+a)cos^2(-a-pai) [tan(pai-a)cos(2pai-a)sin(-a+3pai/2)]/[cos(-a-pai)sin(-pai-a)]= 已知a,b属于(3pai/4,pai),sin(a+b)=-3/5,sin(b-pai/4)=12/13则cos(a+pai/4)=多少 tana=m 则[sin(a+3pai)+cos(pai+a)]/[sin(-a)-cos(pai+a)] [sin^2(a+pai)cos(pai+a)cos(-a-2pai)]/[tan(pai+a)sin^3(pai/2+a)sin(-a-2pai)]= 若tan(5pai+a)=m,则sin(a-3pai)+cos(pai-a/sin(-a)-cos(pai+a)的值为 [cos(a-pai/2)]/[sin(5pai/2+a)]*sin(a-2pai)cos(2pai-a)= cos(a+b)=3/5 sin(b-pai/4)=5/13 a,b 属于(0,pai/2) 求cos(a+pai/4) sin（a+3pai/4）=5/13,cos（pai/4-b）=3/5,且-pai/4〈a〈pai/4,pai/4〈b〈3pai/4,求cos2（a-b）? 化简：sin(2pai-a)cos(pai a)/cos(pai-a)sin(3pai-a) 已知cos(a-pai/6)+sina=4根3/5,求sin(a+7pai/6)的值 已知cos(a-pai/6)+sina=4根3/5,求sin(a+7pai/6)的值 已知cos(a-pai/6)+sina=4√3/5,则sin(a+7/6pai)的值是? 已知sin(a-pai/4)=1/3,则cos(a+pai/4)=? cos(a+pai/4)=3/5,pai/2 sin(a-3pai)cos(pai-a) / cos(pai/2 - a)cos(pai+a)sin(pai/2 + a) 已知sin(3pai/4+a)=5/13,cos(pai/4-b)=3/5,且0 已知a,b属于（x+pai/3),sin(a+b)=-3/5,sina(b-pai/4)=12/13,则cos(a+pai/4)=?