Two straight lines are drawn inside a triangle to create 4 regions. The areas of each region are shown. What number goes in the “?”

$ABCD$ is a square. $M$ is the midpoint of side $AB$.
What fraction of the total area is shaded in blue?

A block $ABCD$ has dimensions $AB=6$, $BC=8$, and $BD=10$. It rolls along line $l$ without slipping until the side $AB$ is at the bottom (as shown).
Imagine there is a light at point B and it creates a path.
a) Find the length of this path. Give your answer in terms of $\pi$
b) Find the area of the region made by this path and line $l$.