①已知cos(π/4-a)=3/5,sin(3π/4+b)=5/13,其中π/4

①已知cos(π/4-a)=3/5,sin(3π/4+b)=5/13,其中π/4 已知sin[a-b]cos a-cos[b-a]sin a=3/5,b是第三象限角,求sin[b+5π/4]的值 高一数学已知sin(π/2-b)*cos(a+b)-sin(π+b)*sin(a+b)=3/5其中a∈(3π/2,2π) 已知a,b属于(3π/4,π),sin(a+b)=-3/5,sin(b-π/4)=12/13,则cos(a+4/π)= 已知A B属于3π/4到π,SIN(A+B)=-3/5,SIN(B-π/4)=12/13,求COS(A+π/4 已知0<A<π/2<B<π,cos(B-π/4)=1/3,sin(A+B)=4/5求cos(a+ 已知角ab sin(a+b)=-3/5 sin(b-π/4)=12/13 求cos(a+π/4)) 答案是-56/65 已知角ab sin(a+b)=-3/5 sin(b-π/4)=12/13 求cos(a+π/4)) 已知sin(a+b)=-3/5,cos(a-b)=12/13,且π/2 急：：已知sin(3π+a)=2cos(a-4π),求(5sin(π/2+a)+cos(π/2-a))/(2cos(π+ 已知sin(a-3π）=2cos(a-4π),求(sin(π-a)+5cos((3π/2)-a))/(2sin(3π/2 已知方程sin（a-3π）=2cos(a-4π）,求 [sin（π-a)+5cos(2π-a)]/[2sin(3π/2-