In this quiz, we test our understanding of how to find missing interior angles of a polygon.

Try to answer the questions before checking the answers at the bottom of the page.

Instructions

Use the formula:

Sum of Interior Angles \(= (n − 2) × 180^\circ\)

For a regular polygon, divide the sum by the number of angles.

For an irregular polygon, subtract the known angles from the total sum.

Questions

Question 1

What is each interior angle of a regular triangle?

A) \(30^\circ\)
B) \(45^\circ\)
C) \(60^\circ\)
D) \(90^\circ\)

Question 2

What is each interior angle of a regular quadrilateral?

A) \(60^\circ\)
B) \(90^\circ\)
C) \(120^\circ\)
D) \(180^\circ\)

Question 3

What is each interior angle of a regular pentagon?

A) \(90^\circ\)
B) \(100^\circ\)
C) \(108^\circ\)
D) \(120^\circ\)

Question 4

What is each interior angle of a regular hexagon?

A) \(100^\circ\)
B) \(108^\circ\)
C) \(120^\circ\)
D) \(135^\circ\)

Question 5

A triangle has angles \(40^\circ, 90^\circ,\) and \(x\).

Find \(x\).

A) \(40^\circ\)
B) \(50^\circ\)
C) \(60^\circ\)
D) \(90^\circ\)

Question 6

A quadrilateral has angles \(50^\circ, x, 130^\circ,\) and \(50^\circ\).

Find \(x\).

A) \(100^\circ\)
B) \(120^\circ\)
C) \(130^\circ\)
D) \(150^\circ\)

Question 7

A pentagon has angles \(90^\circ, 90^\circ, 130^\circ, x,\) and \(130^\circ\).

Find \(x\).

A) \(90^\circ\)
B) \(100^\circ\)
C) \(110^\circ\)
D) \(120^\circ\)

Question 8

A hexagon has angles \(90^\circ, 120^\circ, x, 40^\circ, 270^\circ\), and \(90^\circ\).

Find \(x\).

A) \(100^\circ\)
B) \(110^\circ\)
C) \(120^\circ\)
D) \(130^\circ\)

Question 9

Which formula gives the sum of the interior angles of a polygon?

A) \(n × 180^\circ\)
B) (\(n − 1) × 180^\circ\)
C) \((n − 2) × 180^\circ\)
D) \((n + 2) × 180^\circ\)

Question 10

How do we find a missing angle in an irregular polygon?

A) Divide the total sum by \(2\)
B) Add all the known angles to the total sum
C) Subtract the known angles from the total sum
D) Multiply the number of sides by \(180^\circ\)

Answer Key

1. C) \(60^\circ\)
2. B) \(90^\circ\)
3. C) \(108^\circ\)
4. C) \(120^\circ\)
5. B) \(50^\circ\)
6. C) \(130^\circ\)
7. B) \(100^\circ\)
8. B) \(110^\circ\)
9. C) \((n − 2) × 180^\circ\)
10. C) Subtract the known angles from the total sum

Practice

• More Examples

• Take the Quiz (Current page)

Continue Learning

1. Sum of Interior Angles of a Polygon (Proof)
2. Find Missing Interior Angles of a Polygon (Examples)
3. Why Regular and Irregular Polygons Have Different Angle Formulas?

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