Answer:
The sum of the measures of the angles of a convex quadrilateral is 360° as a convex quadrilateral is made of two triangles. Yes, this property also holds true for a quadrilateral which is not convex. This is because any quadrilateral can be divided into two triangles.
Answer:
12.56 mm²
Step-by-step explanation:

Plug the given values into the area equation

Therefore, the area of the circle is 12.56 mm².
I hope this helps!
19. No
20. No
21. Yes
23. 1.8 miles