4.在△ABC已知c=10,又知cosA/cosB=b/a=4/3,则边a=________,b=________

4.在△ABC已知c=10,又知cosA/cosB=b/a=4/3,则边a=________,b=________
4.在△ABC已知c=10,又知cosA/cosB=b/a=4/3,则边a=________,b=________

4.在△ABC已知c=10,又知cosA/cosB=b/a=4/3,则边a=________,b=________
cosA/cosB=b/a=sinB/sinA
∴sin2A=sin2B,∵a≠b===>2A≠2B
∴2A=180º-2B===>A+B=90º====>C=90º
∴a=6,b=8

sinA/sinB=a/b=4/3
所以 sinA/sinB=cosB/cosA
sinAcosA-sinBcosB=0
sin2A-sin2B=0
2A+2B=180
A+B=90
又c=10
所以 b=8 a=6