MathNet 2019-part-04 — 184 problems (EN–VI) Question 171

In square $ABCD$ with side length $1$, $E$ is the midpoint of $AB$ and $F$ is the midpoint of $BC$. The line segment $EC$ intersects $AF$ and $DF$ at $G$ and $H$, respectively. Find the area of quadrilateral $AGHD$.