(1)解方程x1=1/2,x2=1/3,TAN(A)+TAN(B)=5/6,TAN(A)*TAN(B)=1/6
(2)tan(A+B)=[TAN(A)+TAN(B)]/[1-(TAN(A)*TAN(B)]
=1
(3)A+B=45°
(4)C=135°
C=90°,SINA*SINB=SINA*COSA=1/2*SIN(2A)
90°>A>0,180°>2A>0
当2A=90°时,sinA*sinB取最大值1/2
(1)解方程x1=1/2,x2=1/3,TAN(A)+TAN(B)=5/6,TAN(A)*TAN(B)=1/6
(2)tan(A+B)=[TAN(A)+TAN(B)]/[1-(TAN(A)*TAN(B)]
=1
(3)A+B=45°
(4)C=135°
C=90°,SINA*SINB=SINA*COSA=1/2*SIN(2A)
90°>A>0,180°>2A>0
当2A=90°时,sinA*sinB取最大值1/2