cos(pi/4-a)=3/5 sin(3pi/4+b)=5/13 求sin(a+b)
a,b∈(3pi/4,pi),sin(a+b)=-3/5,sin(b-pi/4)=12/13,则cos(a+pi/4)=
已知a,b,属于(3pi/4,pi),sin(a+b)=-3/5,sin(b-pi/4)=12/13,则cos(a+pi
a*sin(pi/4 - x) - b*cos(pi/4 - x) = a*sin(pi/4 + x) - b*cos(
已知pi/4<a<b<pi/2,且sin(a+b)=4/5,cos(a-b)=12/13,求sina2a的值.
1,已知sin(a-b)cosa-cos(b-a)sina=3/5,b是第三象限角,求sin(b+5pi/4)的值
三角形ABC中sin(2Pi-A)=-根号2cos(3Pi/2+B)根号3cos(2Pi-A)=根号2sin(Pi/2+
是否存在a属于(-pi/2,pi/2),b属于(0,pi),使等式sin(3Pi-a)=根号2cos(pi/2)-b),
tana=2求sin(pi-a)cos(2pi-a)sin(-a+3pi/2)/tan(-a-pi)sin(-pi-a)
f(a)=sin(pi-a)cos(2pi-a)tan(-a+3pi/2)/cos(-pi-a) 求 f(-31pi/3
sin(a+b)=-1/3cosb=2根号6/5,a属于(3PI/2,2PI) b属于(0,PI/2)求cosa
第一题 cos(a+b)=4/5.cos(a-b)= -4/5 .a+b∈[7pi/4,2pi].a-b∈[3pi/4,
cosa=2/3 a是第四象限角求sin(a-2Pi)+sin(-a-3Pi)cos(a-3Pi)/cos(Pi-a)-