Other quadrilaterals and polygons

Back to basics: this unit is about the basic stuff that everyone supposedly knows:

Do you know the area formulas for all common quadrilaterals?
Can you easily work out the angles of arbitrarily large regular polygons?
How about counting their diagonals?

Examples

Example

What’s the measurement of the interior angle of a $12$ -gon?

(spoiler)

If you used the formula, then you get full credit. Good enough.

But if you also wanted style points for cleverness, then you divided the sum of the exterior angles (always $36 0^{o}$ ) by $12$ to get that the exterior angles measure $3 0^{o}$ each, and thus the interior angles measure $15 0^{o}$ each.

What to do

If everything above was old news to you, then this section should be no problem. Click “complete” below, and we’ll add all the relevant quizzes to your deck. Then, during your short daily practice, we’ll occasionally quiz you on this knowledge in a way that etch it into your memory for good.
If some or all of this was new to you, then you should still click “complete” below, and add it to your quizzes, but I recommend against adding anything else for today. Instead, work with these new cards for today, and consider adding more fresh knowledge tomorrow. You might also do a bit of research to refresh (or learn for the first time) the rules given above.