Common Core: 8th Grade Math : Geometry

Study concepts, example questions & explanations for Common Core: 8th Grade Math

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Example Questions

Example Question #431 : Grade 8

Find the length of the hypotenuse of the following right triangle.

12

Possible Answers:

\displaystyle 8

\displaystyle \sqrt{69}

\displaystyle \sqrt{66}

\displaystyle \sqrt{65}

Correct answer:

\displaystyle \sqrt{65}

Explanation:

Recall the Pythagorean Theorem, which is used to find the length of the hypotenuse.

For any triangle with leg lengths of \displaystyle a and \displaystyle b,

13

\displaystyle \text{Hypotenuse}^2=a^2+b^2

Take the square root of both sides to find the length of the hypotenuse.

\displaystyle \text{Hypotenuse}=\sqrt{a^2+b^2}

Plug in the given values to find the length of the hypotenuse.

\displaystyle \text{Hypotenuse}=\sqrt{7^2 + 4^2}=\sqrt{65}

Example Question #61 : Geometry

Right_triangle

Refer to the above diagram, which depicts a right triangle. What is the value of \displaystyle x?

Possible Answers:

\displaystyle 13

\displaystyle 3 \sqrt{ 13}

\displaystyle 10\sqrt{2}

\displaystyle 12

\displaystyle 9\sqrt{3}

Correct answer:

\displaystyle 3 \sqrt{ 13}

Explanation:

By the Pythagorean Theorem, which says \displaystyle a^2+b^2=c^2\displaystyle c being the hypotenuse, or \displaystyle x in this problem. 

\displaystyle x^{2} = 6^{2} + 9^{2}

\displaystyle x^{2} = 36 + 81

\displaystyle x^{2} = 117

\displaystyle x =\sqrt{ 117}

Simply

\displaystyle \sqrt{ 9} \cdot \sqrt{ 13}

\displaystyle 3 \sqrt{ 13}

Example Question #323 : Triangles

Find the length of the hypotenuse of the following right triangle.

9

Possible Answers:

\displaystyle 4\sqrt5

\displaystyle \sqrt{29}

\displaystyle 2\sqrt{29}

\displaystyle 3\sqrt{21}

Correct answer:

\displaystyle 2\sqrt{29}

Explanation:

Recall the Pythagorean Theorem, which is used to find the length of the hypotenuse.

For any triangle with leg lengths of \displaystyle a and \displaystyle b,

13

\displaystyle \text{Hypotenuse}^2=a^2+b^2

Take the square root of both sides to find the length of the hypotenuse.

\displaystyle \text{Hypotenuse}=\sqrt{a^2+b^2}

Plug in the given values to find the length of the hypotenuse.

\displaystyle \text{Hypotenuse}=\sqrt{10^2 + 4^2}=\sqrt{116}

Simply:

\displaystyle \sqrt{4}\cdot\sqrt{29}

\displaystyle 2\sqrt{29}

Example Question #432 : Grade 8

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.

1

Possible Answers:

Correct answer:

Explanation:

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or \displaystyle 90^\circ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle." 

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms:

\displaystyle a^2+b^2=c^2

2

We can use the formula and substitute the known side lengths from the problem to solve for the missing side length:

\displaystyle 9^2+8^2=c^2

\displaystyle 81+64=c^2

\displaystyle 145=c^2

\displaystyle \sqrt{145}=\sqrt{c^2}

\displaystyle 12.04=c

or

\displaystyle c=12

Example Question #433 : Grade 8

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.


3

Possible Answers:

Correct answer:

Explanation:

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or \displaystyle 90^\circ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle." 

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms:

\displaystyle a^2+b^2=c^2

2

We can use the formula and substitute the known side lengths from the problem to solve for the missing side length:

\displaystyle 12^2+35^2=c^2

\displaystyle 37=c

 

Example Question #123 : Geometry

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.


4

Possible Answers:

\displaystyle 15\text{ cm}

\displaystyle 18\text{ cm}

\displaystyle 17\text{ cm}

\displaystyle 16\text{ cm}

\displaystyle 14\text{ cm}

Correct answer:

\displaystyle 17\text{ cm}

Explanation:

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or \displaystyle 90^\circ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle." 

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms:

\displaystyle a^2+b^2=c^2

2

We can use the formula and substitute the known side lengths from the problem to solve for the missing side length:

\displaystyle 8^2+15^2=c^2

\displaystyle 64+225=c^2

\displaystyle 289=c^2

\displaystyle \sqrt{289}=\sqrt{c^2}

\displaystyle 17=c

 

Example Question #124 : Geometry

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.


5

Possible Answers:

Correct answer:

Explanation:

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or \displaystyle 90^\circ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle." 

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms:

\displaystyle a^2+b^2=c^2

2

We can use the formula and substitute the known side lengths from the problem to solve for the missing side length:

\displaystyle 24^2+32^2=c^2

\displaystyle 40

 

Example Question #125 : Geometry

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.


6

Possible Answers:

Correct answer:

Explanation:

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or \displaystyle 90^\circ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle." 

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms:

\displaystyle a^2+b^2=c^2

2

We can use the formula and substitute the known side lengths from the problem to solve for the missing side length:

\displaystyle 72^2+21^2=c^2

\displaystyle 75=c

 

Example Question #33 : Apply The Pythagorean Theorem To Determine Unknown Side Lengths In Right Triangles: Ccss.Math.Content.8.G.B.7

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.


7

Possible Answers:

Correct answer:

Explanation:

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or \displaystyle 90^\circ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle." 

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms:

\displaystyle a^2+b^2=c^2

2

We can use the formula and substitute the known side lengths from the problem to solve for the missing side length:

\displaystyle 12^2+5^2=c^2

\displaystyle 144+25=c^2

\displaystyle 169=c^2

\displaystyle \sqrt{169}=\sqrt{c^2}

\displaystyle 13=c

 

Example Question #31 : Apply The Pythagorean Theorem To Determine Unknown Side Lengths In Right Triangles: Ccss.Math.Content.8.G.B.7

Calculate the length of the missing side of the provided triangle. Round the answer to the nearest whole number.


8

Possible Answers:

Correct answer:

Explanation:

The provided triangle is a right triangle. We know this because the angle marker in the left corner of the triangle indicates that the triangle possesses a right or \displaystyle 90^\circ angle. When a triangle includes a right angle, the triangle is said to be a "right triangle." 

We can use the Pythagorean Theorem to help us solve this problem.

The Pythagorean Theorem states that for right triangles, the square of the hypotenuse is equal to the sum of the square of the other two sides. In other terms:

\displaystyle a^2+b^2=c^2

2

We can use the formula and substitute the known side lengths from the problem to solve for the missing side length:

\displaystyle 16^2+12^2=c^2

\displaystyle 256+144=c^2

\displaystyle 400=c^2

\displaystyle \sqrt{400}=\sqrt{c^2}

\displaystyle 20=c

 

 

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