How to Find Missing Angels in Quadrilateral Shapes? (+FREE Worksheet!)
The parallelogram is a simple quadrilateral with two pairs of parallel sides. The size of the opposite sides and the opposite angles in the parallelogram are equal. \({\angle}A+{\angle}B+{\angle}C+{\angle}D=360^{\circ}\).
Finding Quadrilateral angles Example 1:
Find the missing angle in the quadrilateral.
Solution: We have been given three angles and need to determine the measure of the fourth. Add together the measures of the known angles.
\(125^{\circ}+90^{\circ}+105^{\circ}=320^{\circ}\)
Subtract the sum from \(360^{\circ}\) to determine what remains for the fourth angle. \(360^{\circ}-320^{\circ}=40^{\circ}\)
The measure of the unknown angle is \(40^{\circ}\)
Finding Quadrilateral angles Example 2:
Find the missing angle in the quadrilateral.
Solution: We have been given three angles and need to determine the measure of the fourth. Add together the measures of the known angles.
\(78^{\circ}+85^{\circ}+57^{\circ}=220^{\circ}\)
Subtract the sum from \(360^{\circ}\) to determine what remains for the fourth angle. \(360^{\circ}-220^{\circ}=140^{\circ}\)
The measure of the unknown angle is \(140^{\circ}\)
Exercises for Finding Quadrilateral angles
Find the missing angle in each quadrilateral.
1)\(x=\)
2)\(x=\)
3)\(x=\)
- \(x=75^{\circ}\)
- \(x=70^{\circ}\)
- \(x=62^{\circ}\)
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