Angle Measures in an Isosceles Trapezoid
publish date: 2026/05/16 01:15:5.393598 UTC
Trapezoid ABCD is an isosceles trapezoid where the top base segment AB is parallel to the bottom base segment DC (\(AB \parallel DC\)). The non-parallel sides (legs) AD and BC are equal in length.
If the measure of interior angle D is \(70^\circ\), determine the measure of interior angle C.
Correct Answer
Explanation
An isosceles trapezoid possesses line symmetry passing vertically through the midpoints of its parallel bases. Because of this symmetry, its base angles are perfectly identical mirror images of each other.
In this figure, \(\angle D\) and \(\angle C\) both lie along the bottom base segment DC. Therefore, they are corresponding base angles and hold equal metrics:
\[ m\angle C = m\angle D = 70^\circ \]
Reference
Mathematics for college students