已知sin(A+π/4)=7根号2/10,A属于(π/4,π/2)求cosA的值

已知sin(a-π/4)=-根号2/10,0 已知sin(A+π/4)=7根号2/10,A属于(π/4,π/2)求cosA的值 已知sin(π/4-a)sin(π/4+a)=六分之根号二(0 已知sin(π/6+a)=（根号3）/3,求sin(2π/3+a)? 已知x+y=根号2sin(a+π/4),x-y=根号2sin(a-π/4),求证x^2+y^2=1 已知x+y=根号2sin(a+π/4),x-y=根号2sin(a-π/4),求证x^2+y^2=1 已知sin(a+π/3)+sina=-(4倍根号下3)/5,-π/2 已知sin(a+π/3)+sina=-4根号3/5,-π/2 已知sin(a+π/3)+sina=-4根号3/5 -π/2 已知sin（a—π/4）=7倍根号2/10,cos2a=7/25,求sina及tan（a+π/3）的值 已知sin(a-π/4）=7根号2/10,cos2a=7/25,求sina及tan(a+π/3） 已知sin(a-π/4）=7根号2/10,cos2a=7/25,求sina及tan(a+π/3） 已知sin a-cos a=根号2,且0 已知sin(3π -a)=根号2sin(2π +b),根号3cos(-a)=-根号2cos(π +b)且0 已知sin(3π -a)=根号2sin(2π +b),根号3cos(-a)=-根号2cos(π +b)且0 已知a为第二象限角,且sina=根号15/4,求sin(π-a)/((sin(a+π/2)+cosa+1) 已知sin(a-45°)=(7倍根号2)/10,cos2a=7/25,求sin a及tan(a+60°)的值 已知sin(a+π/6)+cosa=4/5倍根号3,则sin(a+π/3)=