问题
选择题
△ABC中,若A=60°,a=
|
答案
由正弦定理可得 2r=
=a sinA
=2,(r为外接圆半径);3 sin60°
=a+b-c sinA+sinB-sinC
=2r=2,2rsinA +2rsinB - 2rsinC sinA+sinB-sinC
故选A.
△ABC中,若A=60°,a=
|
由正弦定理可得 2r=
=a sinA
=2,(r为外接圆半径);3 sin60°
=a+b-c sinA+sinB-sinC
=2r=2,2rsinA +2rsinB - 2rsinC sinA+sinB-sinC
故选A.