Question

casuiciICnIS. TS PULSUL TUTUWg.
Theorem 10.11 : The sum of either pair of opposite angles of a
quadrilateral is 180°.​

Answer 1

Answer:

Proof: The sum of the measures of the interior angles of any quadrilateral can be found by breaking the quadrilateral into two triangles. Since the measure of the interior angles of any triangle equals 180 degrees, each of the two triangles will contribute 180 degrees to the total for the quadrilateral.

So the measure of the interior angles of a convex quadrilateral is the same as the sum of the measures of the interior angles of two triangles, or 360 degrees.