This diagram gives you many big hints.
Can you find reasons and explanations
for how it all fits together as it appears to do?
It is important to bear in mind that the angles around a point add up to
and the angles on a straight line make
. When you have found the angles in the quadrilaterals does this suggest that
the quadrilaterals are a special type?
See how 3 copies of triangle D and two chosen from triangles r, s and t fit
into the quadrilaterals like
pieces of a jigsaw. Can you explain why it works?