即sinBcosA?2sinAcosA,当cosA?0时,
A??2,
B??6,
a?433b?233,,
当cosA?0时,得sinB?2sinA,由正弦定理得b?2a,
?a?b?ab?4,2343?a?b?b?2a,3,3. 联立方程组?解得
1223322所以△ABC的面积
S?absinC?.
- 11 -
即sinBcosA?2sinAcosA,当cosA?0时,
A??2,
B??6,
a?433b?233,,
当cosA?0时,得sinB?2sinA,由正弦定理得b?2a,
?a?b?ab?4,2343?a?b?b?2a,3,3. 联立方程组?解得
1223322所以△ABC的面积
S?absinC?.
- 11 -