Let the measure of BCD = aº Because BCD and BAD form a circle, and a circle measures 360°, the measure of BAD is 360 -
a”. Because of the theorem, mzA= degrees and m C = 360 -2 degrees. The sum of the measures of
angles A and Cis+350 – a degrees, which is equal to 360°, or 180°. Therefore, angles A and C are supplementary
because their measures add up to 180° Angles B and D are supplementary because the sum of the measures of the
angles in a quadrilateral is 360° MZA+ m2C + m2B + m2D = 360° and using substitution, 180° + m2B + m2D = 360°
so mZB + m2D = 180°
What is the missing information in the paragraph proof?
inscribed angle
polygon interior angle sum
quadrilateral angle sum
angle bisector