[The angle between two intersecting chords and two secants]

A circle is divided by points $A, B, C, D$ such that $\sim A B:-B C:-C D:-D A=3: 2: 13: 7$. Chords $A D$ and $B C$ are extended to intersect at point $M$.

Find the angle $AMB$
$\angle A M B=1 / 2(-D C--A B)=1 / 2 \cdot \cdot 10 / 25 \cdot 360^{\circ}=72^{\circ}$

![](https://cdn.mathpix.com/cropped/2024_05_06_4541620ef230b5fef331g-17.jpg?height=526&width=481&top_left_y=1158&top_left_x=797)

Answer

$72^{\circ}$.