Table of Contents

## How do you find the angle of an unknown angle?

To determine to measure of the unknown angle, be sure to use the total sum of 180°. If two angles are given, add them together and then subtract from 180°. If two angles are the same and unknown, subtract the known angle from 180° and then divide by 2.

### Do angles in a quadrilateral equal 360?

Quadrilaterals are composed of two triangles. Seeing as we know the sum of the interior angles of a triangle is 180°, it follows that the sum of the interior angles of a quadrilateral is 360°.

**Why do angles in a quadrilateral add up to 360?**

Another way to calculate the sum of the interior angles of a polygon is to see how many triangles the shape is composed of. Quadrilaterals are composed of two triangles. Seeing as we know the sum of the interior angles of a triangle is 180°, it follows that the sum of the interior angles of a quadrilateral is 360°.

**How do you find unknown angles in a quadrilateral?**

We can extend this concept to find unknown angles within quadrilaterals given the measure of any three angles. We can determine the unknown angle measure by subtracting the sum of the three known angles from 360°. Angles in a quadrilateral (that is a 4 sided shape) add up to 360 degrees.

## When do you subtract angles in a quadrilateral?

If you have a rectangle or square, each of the angles measures 90°. If you have a parallelogram or rhombus, the opposite angles are the same and the consecutive angles are supplementary. For other types of quadrilaterals you may need to add the given angles and then subtract from 360°.

### What are the interior angles of a quadrilateral?

We must first recognize that any given quadrilateral is composed of two triangles. Since the sum of the interior angles of a triangle is 180°, then the sum of the interior angles of the quadrilateral would be 360° (180° + 180° = 360°). We can also cut out quadrilaterals of various shapes and sizes.

**How to find the measure of a fourth angle?**

We have been given three angles and need to determine the measure of the fourth. Step 1: Add together the measures of the known angles. Step 2: Subtract the sum from 360° to determine what remains for the fourth angle. The measure of the unknown angle is 145°. Here we have a parallelogram.