Quadrilateral abcd is inscribed in this circle.

what is the measure of angle a?

enter your answer in the box.

°

The sum of all interior angles in a polygon is

180(n-2), where n = sides, well, this is a QUADrilateral, so it has 4 sides, so the total is 360°.

now, let's find what angle C is first,



now, recall the "inscribed quadrilateral conjecture", where opposite angles are "supplementary angles", thus