Geometry help, please?

Question

I'm doing an indirect proof and I have to negate the idea that a certain quadrilateral is not convex. My first statement, of course, is: Assume temporarily that Quad. EFGH is a convex quadrilateral. This implies that..."? What would this imply? I've been given the measures of the angles, but what does being convex have to do with angles?

Answer 1

in a convex quadrilateral, none of the internal angles is greater than 180 degrees. So assuming that quad EFGH is convex would imply that each of the internal angles are < 180 degrees.