A parallelogram has an interior angle measuring 81°. Which MUST also be the measure of an interior angle of the parallelogram?
A) 9°
B) 19°
C) 49°
D) 89°
E) 99°
99º, because the sum of all 4 of the interior angles of the parallelogram must be 360º. We know that if one angle measures 81º the other angle on the opposite side must measure 81º.. so 81+81=162 360-162=198 198 - 2(number of remaining angles) = 99º
