TIMO 2017 - Senior Secondary (Grades 10-12) - Heat Round - Paper 5 Question 20

Quadrilateral $ABCD$ has $AB=15$ cm, $BC=7$ cm, $CD=20$ cm, $DA=25$ cm. Let $x$ be the angle between the diagonals with $0^\circ\le x\le90^\circ$. Find $x$.