Angle Relationships involving Quadrilaterals

Lesson 3 (4th Weeks)TEKS 6.6B

Quadrilateral

•Polygon with 4 sides

Special relationship among angles in quadrilaterals all 6th grade students should know

• The sum of the measures of the 4 angles in a quadrilateral equals 360°.

• Rectangles and squares have 4 right (90°) angles.

(4 x 90° = 360°)

• In parallelograms and rhombi, both pair of opposite angles are congruent and the sum of the measures of any two consecutive angles is 180.

How to determine the missing angle measure in a quadrilateralStep 1: Add together the measures of the 3 known angles.

Step 2: Subtract the sum from 360°.

Example

Find the measure of N in the figure below.

The sum of the measures of the angles in a quadrilateral is 360°.

M measure 140°.

O & P measure 90°.

140°90°90°+0°23

2

360°320° 0°4

-

m N= 40°