Finding the length of a side of a quadrilateral given 2 sides and two angles
By Andrew Adams •
In the quadrilateral $ABCD$, $AD$ is parallel to $BC$, $\angle C = 2\angle A$, $CD=3$, and $BC=2$, What is $AD$?
I think I have to making a line bisecting $AC$, but I am not sure.
$\endgroup$ 01 Answer
$\begingroup$Let $CE$ (here $E \in AD$) be the bisector of $\angle C$. Then $AD = AE+ED = BC + CD$.
$\endgroup$