Challenging Quiz on Geometry Concepts

  • 8th Grade
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| By Catherine Halcomb
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| Attempts: 11 | Questions: 18 | Updated: Feb 26, 2026
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Question 1 / 19
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1) What is the Pythagorean theorem formula?

Explanation

The Pythagorean theorem describes the relationship between the sides of a right triangle. In this theorem, \(a\) and \(b\) represent the lengths of the two legs, while \(c\) represents the length of the hypotenuse. The formula \(a^2 + b^2 = c^2\) states that the sum of the squares of the lengths of the legs equals the square of the length of the hypotenuse. This fundamental principle is essential in geometry and is widely used in various applications, including physics, engineering, and computer science.

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About This Quiz
Challenging Quiz On Geometry Concepts - Quiz

This challenging quiz on geometry concepts evaluates key principles such as the Pythagorean theorem, angle sums, and properties of triangles and polygons. It is essential for learners to reinforce their understanding of geometric relationships and calculations, making it a valuable tool for mastering geometry.

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2) In the Pythagorean theorem, which side is c?

Explanation

In the Pythagorean theorem, the hypotenuse is defined as the longest side of a right triangle, opposite the right angle. It is represented by the variable 'c' in the equation \(a^2 + b^2 = c^2\), where 'a' and 'b' are the lengths of the other two sides, known as the legs. This relationship highlights that the hypotenuse is always the longest side in a right triangle, making it a fundamental aspect of this theorem in geometry.

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3) A right triangle has legs 9 and 12. What is the hypotenuse?

Explanation

To find the hypotenuse of a right triangle with legs measuring 9 and 12, we use the Pythagorean theorem, which states that the square of the hypotenuse (c) is equal to the sum of the squares of the legs (a and b). Here, a = 9 and b = 12. Calculating, we have c² = 9² + 12² = 81 + 144 = 225. Taking the square root of 225 gives us c = 15. Thus, the hypotenuse is 15.

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4) How do you find the perimeter of a shape when given side lengths?

Explanation

To find the perimeter of a shape, you need to sum the lengths of all its sides. If any side lengths are missing, you can use relevant formulas or properties of the shape (like the Pythagorean theorem for triangles) to calculate those lengths. Once you have all side lengths, simply add them together to get the total perimeter. This method ensures that you account for every side, providing an accurate measurement of the shape's boundary.

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5) What is the formula for the angle sum of any polygon?

Explanation

The formula for the angle sum of a polygon is derived from dividing the polygon into triangles. A polygon with \( n \) sides can be divided into \( n - 2 \) triangles. Since each triangle has an angle sum of 180°, the total angle sum of the polygon is \( (n - 2) \times 180° \). This relationship holds true for any polygon, regardless of the number of sides, making it a fundamental concept in geometry.

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6) What is the formula for each interior angle of a regular polygon?

Explanation

In a regular polygon, the sum of the interior angles can be calculated using the formula (n - 2) * 180°, where n represents the number of sides. To find the measure of each interior angle, this sum is divided by n, leading to the formula (n - 2) * 180° / n. This formula accounts for the fact that as the number of sides increases, each angle's measure also increases, reflecting the geometric properties of regular polygons.

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7) What is the interior angle of a regular octagon? (n = 8)

Explanation

To find the interior angle of a regular octagon, we use the formula for the interior angle of a regular polygon: \((n-2) \times 180° / n\), where \(n\) is the number of sides. For an octagon, \(n = 8\). Plugging in the values, we get \((8-2) \times 180° / 8 = 6 \times 180° / 8 = 1080° / 8 = 135°\). Thus, each interior angle of a regular octagon measures 135°.

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8) What is the angle sum of an octagon?

Explanation

To find the angle sum of an octagon, we can use the formula for the sum of interior angles of a polygon, which is (n - 2) × 180°, where n is the number of sides. For an octagon, n equals 8. Thus, the calculation is (8 - 2) × 180° = 6 × 180° = 1080°. This indicates that the total measure of all interior angles in an octagon is 1080 degrees.

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9) Supplementary angles add up to what?

Explanation

Supplementary angles are defined as two angles whose measures add up to 180 degrees. This property is fundamental in geometry, particularly in the study of angle relationships. For example, if one angle measures 120 degrees, the supplementary angle would measure 60 degrees, since 120° + 60° = 180°. Understanding supplementary angles is essential for solving various geometric problems, including those involving parallel lines and transversals.

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10) Complementary angles add up to what?

Explanation

Complementary angles are defined as two angles whose measures add up to 90 degrees. This concept is fundamental in geometry and is often used in various applications, such as in right triangles, where one angle is acute and the other complements it to form a right angle. Understanding complementary angles is essential for solving problems related to angles and triangles in mathematics.

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11) Vertical angles are always...?

Explanation

Vertical angles are formed when two lines intersect, creating two pairs of opposite angles. By the properties of angles, these opposite angles are always equal in measure, making them congruent. This relationship holds true regardless of the size or orientation of the intersecting lines, ensuring that vertical angles maintain their equality. Thus, whenever two angles are vertical, they will always have the same degree measure, confirming that vertical angles are congruent.

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12) If two angles form a straight line, what is their sum?

Explanation

When two angles form a straight line, they are supplementary angles, meaning their measures add up to 180 degrees. A straight line itself is defined as having an angle of 180 degrees. Therefore, regardless of the individual measures of the angles, their total will always equal 180 degrees when they combine to create a straight line.

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13) If vertical angles are 67°, what is the other vertical angle?

Explanation

Vertical angles are formed when two lines intersect, creating two pairs of opposite angles that are equal. If one angle measures 67°, the angle directly opposite it, which is the other vertical angle, must also measure 67°. This property of vertical angles ensures that they are always equal, confirming that the other vertical angle in this scenario is also 67°.

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14) If 40° + x = 180°, what is x?

Explanation

To find the value of x in the equation 40° + x = 180°, we need to isolate x. This can be done by subtracting 40° from both sides of the equation. So, we have x = 180° - 40°. Calculating this gives us x = 140°. Therefore, x equals 140°, which represents the angle that, when added to 40°, completes the straight angle of 180°.

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15) What is the sum of interior angles in a triangle?

Explanation

The sum of the interior angles in a triangle is always 180°. This is a fundamental property of triangles in Euclidean geometry. It can be understood by dividing a triangle into two right triangles, where the angles add up to 90° each, leading to a total of 180°. This principle holds true regardless of the type of triangle, whether it is scalene, isosceles, or equilateral, making it a key concept in geometry.

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16) What is an exterior angle of a triangle equal to?

Explanation

An exterior angle of a triangle is formed when one side of the triangle is extended. This angle is equal to the sum of the two non-adjacent (remote) interior angles. This relationship is derived from the properties of triangles and can be proven using the triangle's angle sum property, which states that the sum of the interior angles of a triangle is always 180 degrees. Thus, the exterior angle essentially represents the amount by which the sum of the remote interior angles exceeds the adjacent interior angle.

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17) If one interior angle is 95° and the exterior angle next to it is 140°, what is the missing interior angle?

Explanation

In a triangle, the sum of the interior angles is always 180°. Given one interior angle is 95° and the exterior angle adjacent to it is 140°, we can find the missing interior angle. The exterior angle is equal to the sum of the two opposite interior angles. Thus, the equation becomes: 140° = 95° + x, where x is the missing interior angle. Solving for x gives us x = 140° - 95° = 45°. However, we need the angle that complements this to 180°, which leads us to 35° as the missing angle.

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18) If the exterior angle = 120°, what is the sum of the two remote interior angles?

Explanation

In a triangle, the exterior angle is equal to the sum of the two remote interior angles. Given that the exterior angle measures 120°, the sum of the two remote interior angles must also equal 120°. This relationship holds true for all triangles, allowing us to determine that the answer is 120°.

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What is the Pythagorean theorem formula?
In the Pythagorean theorem, which side is c?
A right triangle has legs 9 and 12. What is the hypotenuse?
How do you find the perimeter of a shape when given side lengths?
What is the formula for the angle sum of any polygon?
What is the formula for each interior angle of a regular polygon?
What is the interior angle of a regular octagon? (n = 8)
What is the angle sum of an octagon?
Supplementary angles add up to what?
Complementary angles add up to what?
Vertical angles are always...?
If two angles form a straight line, what is their sum?
If vertical angles are 67°, what is the other vertical angle?
If 40° + x = 180°, what is x?
What is the sum of interior angles in a triangle?
What is an exterior angle of a triangle equal to?
If one interior angle is 95° and the exterior angle next to it is...
If the exterior angle = 120°, what is the sum of the two remote...
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