Missing Angles in a
Quadrilateral - Lesson
Topic Index | Grade 7 Math | Intermediate Test Prep | StudyZone


It is often possible to find a missing angle when given some of the angles of a quadrilateral.

It is important to remember that the sum of the
angles of any quadrilateral is 360
.

 

The two acute angles of a parallelogram are each 45.  What is the angle measure of each obtuse angle?

If the sum of the angles of the parallelogram is 360, and the sum of the two acute angles is 90, we have 270 left between the two obtuse angles.  When we divide the 270 between the two obtuse angles, each angle's measure is 135.

The two obtuse angles of this trapezoid are each 117.  What is the angle measure of each acute angle?

The sum of the angles of the trapezoid is 360.  The sum of the two obtuse angles is 234, leaving 126 between the two acute angles.  126 divided by 2 equals 63 for each acute angle.

In this trapezium, the two acute angles have measures of 35 and 70.  If one obtuse angle measures 145, what is the angle measure of the second obtuse angle? 

The sum of the angles of the trapezium is 360.  The sum of the three given angles is 250.  This leaves 110 for the fourth angle measure.


Ready to answer some practice problems?

 

 
Topic Index | Grade 7 Math | Intermediate Test Prep | StudyZone

Created by Sarah Therrien
Copyright 2001-06 Oswego City School District