Riddle 9

Find as many conceptually distinct interpretations as possible for Riddle 6’s factor of k = 4/3.

Which features there as the constant of proportionality in the medians’ counterpart of Heron’ formula.

Where else in Geometry do technically-related powers of k occur?

Riddle 8

Show that any triangle can be cut into 4 congruent triangles, each of which is similar to the original.

For which quadrilaterals can this be done?

Find a pentagon for which this can be done.