Geometry quiz

Geometry Quiz: Angles, Area, and Shapes

Practice geometry questions about angles, triangles, area, perimeter, circles, volume, and the Pythagorean theorem. Use hints when needed, choose an answer, and review the explanation after each question.

1 Question 1 of 10
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A triangle has angles 40° and 65°. What is the third angle?

Hint: The angles inside a triangle always add up to 180°.
Explanation: Add the known angles: 40° + 65° = 105°. Then subtract from 180°: 180° − 105° = 75°.
2 Question 2 of 10
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What is the area of a rectangle with length 12 and width 5?

Hint: Use the formula: area = length × width.
Explanation: The area of a rectangle is length × width. So 12 × 5 = 60.
3 Question 3 of 10
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What is the perimeter of a square with side length 9?

Hint: A square has 4 equal sides.
Explanation: The perimeter of a square is 4 × side. So 4 × 9 = 36.
4 Question 4 of 10
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A right triangle has legs 6 and 8. What is the hypotenuse?

Hint: Use the Pythagorean theorem: a² + b² = c².
Explanation: Calculate 6² + 8² = 36 + 64 = 100. Therefore c = √100 = 10.
5 Question 5 of 10
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What is the circumference of a circle with radius 7? Use π = 22/7.

Hint: Use the formula: circumference = 2πr.
Explanation: The circumference is 2πr. Substitute r = 7 and π = 22/7: 2 × 22/7 × 7 = 44.
6 Question 6 of 10
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What is the area of a triangle with base 10 and height 6?

Hint: Use the formula: area = 1/2 × base × height.
Explanation: The area of a triangle is 1/2 × base × height. So 1/2 × 10 × 6 = 30.
7 Question 7 of 10
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A straight angle measures how many degrees?

Hint: A straight angle forms a straight line.
Explanation: A straight angle is exactly 180° because it forms a straight line.
8 Question 8 of 10
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What is the volume of a cube with side length 4?

Hint: Use the formula: volume = side³.
Explanation: The volume of a cube is s³. So 4³ = 4 × 4 × 4 = 64.
9 Question 9 of 10
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Two angles are supplementary. One angle is 110°. What is the other angle?

Hint: Supplementary angles add up to 180°.
Explanation: Supplementary angles have a sum of 180°. So the other angle is 180° − 110° = 70°.
10 Question 10 of 10
Not answered

What is the area of a circle with radius 3? Use π = 3.14.

Hint: Use the formula: area = πr².
Explanation: The area of a circle is πr². With r = 3, area = 3.14 × 3² = 3.14 × 9 = 28.26.

Your result

You answered 0 out of 10 questions correctly.

What this quiz checks

These 10 questions test the geometry facts that later problems build on

The quiz covers angle sums, supplementary angles, area and perimeter, circles, volume, and the Pythagorean theorem. These are foundation skills, but they become much more useful when you can recognize which relationship applies inside a less obvious diagram or multi-step problem.

Angle relationships

Use triangle sums and supplementary angles as constraints rather than isolated facts to memorize.

Area and perimeter

Keep one-dimensional and two-dimensional measurements separate, especially in multi-step geometry.

Circle measurements

Distinguish circumference from area and identify whether the problem gives radius or diameter.

Right triangles and volume

Connect squared lengths in right triangles and cubic units in three-dimensional measurement.

Read the diagram

A drawing is evidence only when the problem states or proves the relationship

In more advanced geometry, diagrams are often not drawn to scale. A side that looks longer is not automatically longer, and an angle that looks like 90° is not automatically a right angle. Use labels, markings, coordinates, and theorems as your evidence.

Triangle angle sum

If two angles are known, the third follows from A + B + C = 180°.

Right-triangle condition

The Pythagorean theorem applies only when the triangle is known to be right.

Area information

A base and a perpendicular height determine triangle area; a slanted side is not automatically the height.

Treat labels and markings as facts. Treat visual appearance as a clue only.
A B C 8 12 ?
Right-triangle reasoning

Use the Pythagorean theorem as a relationship, not just a 6-8-10 pattern

Suppose a right triangle has hypotenuse 17 and one leg 8. The unknown leg is not found by adding or subtracting side lengths; the relationship is between their squares.

a² + 8² = 17²
a² + 64 = 289
a² = 225
a = 15
From foundation to high school geometry

The same basic formulas become harder when information is indirect

A direct area or circumference question is only the first layer. High school geometry often hides the needed measurement inside similarity, algebra, coordinates, or another geometric relationship.

Angles → algebra

Instead of giving two numerical angles, a problem may describe them as 3x + 10 and 5x − 6.

Use the angle relationship first, then solve the resulting equation for x.

Area → similarity

If similar figures have linear scale factor 3:5, their areas do not scale 3:5.

Area ratio = 3²:5² = 9:25.

Volume → cubic scale

When every length is multiplied by k, volume is multiplied by k³.

Doubling all dimensions multiplies volume by 8, not by 2.
Circle reasoning

Radius controls both circumference and area, but in different ways

The current quiz asks separately for circumference and area. The important distinction is that circumference changes linearly with radius, while area changes with the square of the radius.

What happens if the radius doubles?

If r becomes 2r, the circumference doubles because r appears to the first power. But the area becomes four times as large because the radius is squared.

C = 2πr → 2C
A = πr² → 4A
Common geometry mistakes

Three errors that make correct formulas produce wrong answers

Using the wrong measurement type

Perimeter and circumference use linear units, area uses square units, and volume uses cubic units.

A rectangle 12 by 5 has area 60 square units, not 60 units.

Confusing radius and diameter

Circle formulas change depending on which quantity the problem gives. Diameter is twice the radius.

If diameter = 14, then radius = 7 before using A = πr².

Using a theorem without its condition

The Pythagorean theorem requires a right triangle; triangle area requires a perpendicular height.

Check the diagram markings or wording before choosing the formula.
Use your result

What to do after this 10-question geometry foundation check

0–4 correct

Review angle sums, perimeter versus area, circle radius/diameter, and the conditions for the Pythagorean theorem.

5–7 correct

Rework the exact topic types you missed, then try problems where the needed measurement is not given directly.

8–10 correct

Move toward similarity, coordinate geometry, trigonometry, circle theorems, and multi-step geometry problems.

Continue from here

Use the foundation quiz as the starting point, not the final geometry level

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