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问题: 求点的轨迹方程

已知△ABC的三个角满足:
cosA+cosB=8(sinC/2)^2
且A(-2,3),B(-2,-1),
求C点的轨迹方程.

解答:

cosA+cosB=8(sinC/2)^2=8(cos(A+B)/2)^2,
2COS(A+B)/2 *COS(A-B)/2=8COS(A+B)/2 *COS(A+B)/2,
COS(A+B)/2[4COS(A+B)/2-COS(A-B)/2]=0
1)COS(A+B)/2=0,(A+B)=90',C(x,y),(Y-3)*(Y-1)/(X+2)*(X+2)=-1,
(X+2)^2+y^2-3y+3=0
2)4COS(A+B)/2-COS(A-B)/2=0