# 4 coplanar points

Geometry Level 3

Let there exist 3 coplanar points $$B$$, $$C$$, and $$D$$ such that $$BC=5$$ and $$CD=7$$ and $$\angle BCD =$$ $$120^\circ$$. $$A$$ is a point in the same plane that lies on the angle bisector of $$\angle BCD$$. Then what should be the value of $$CA$$ so that the points $$B$$, $$A$$ and $$D$$ are collinear?

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