k(AB)=(2-3)/(4-1)=-1/3
AB直線方程為：y-3=-1/3*(x-1)
整理得 x+3y-10=0
設(shè)橢圓參數(shù)方程為x=3cost,y=2sint,0≤t≤π/2
設(shè)橢圓上點C=C(3cost,2sint)
則點C到AB的距離為d=|3cost+6sint-10|/√10
S△ABC=1/2*AB*d
=1/2*√10*|3cost+6sint-10|/√10
=1/2*|3cost+6sint-10|
∵0≤t≤π/2,∴0≤sin≤1,0≤cost≤1,∴3cos+6sint-10<0
∴S△ABC=1/2*[10-3(2sint+cost)]
=1/2*[10-3√5sin(t+u)] (tanu=1/2,u≈0.46=0.15π)
≥1/2*[10-3√5]
∴當(dāng)sin(t+u)=1時,S△ABC取得最小值(10-3√5)/2
此時,t+u=π/2,∴t=π/2-u=0.35π
sin0.35π≈0.89,cos0.35π≈0.45
∴點C坐標(biāo)為C(3cos0.35π,2sin0.35π)=C(1.35,1.78)
