(cosA/2)^2=4/5
2*(cosA/2)^2=8/5
2*(cosA/2)^2-1=3/5
cosA=3/5
sinA=4/5
S三角形=(AB*AC*sinA)/2=6/5
b+c=6
b*c=3
b=3+√6
c=3-√6
a^2=b^2+c^2-2bc*cosA=132/5
a=(2√165)/5
(cosA/2)^2=4/5
2*(cosA/2)^2=8/5
2*(cosA/2)^2-1=3/5
cosA=3/5
sinA=4/5
S三角形=(AB*AC*sinA)/2=6/5
b+c=6
b*c=3
b=3+√6
c=3-√6
a^2=b^2+c^2-2bc*cosA=132/5
a=(2√165)/5