45度<A<135度,0<B<<45度,cos(45-A)=3/5,sin(135+B)=5/13,求sin(A+B)的值.

熱心網(wǎng)友

cos(A-45)=cos(45-A)=3/545度

熱心網(wǎng)友

cos(45-A)=sin(90-45+A)=sin(45+A)=3/590<45+A<180,cos(45+A)=-4/5135<135+B<180,cos(135+B)=-12/13sin(A+B)=-sin(180+A+B)=-[sin(45+A)cos(135+B)+sin(135+B)cos(45+A)]=-[(3/5)*(-12/13)+(5/13)*(-4/5)]=-[-56/65]=56/65

熱心網(wǎng)友

因?yàn)?5