ACT Math : How to find the length of the diagonal of a parallelogram

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #1 :How To Find The Length Of The Diagonal Of A Parallelogram

If a rectangular plot measuresby, what is the length of the diagonal of the plot, in feet?

Possible Answers:

Correct answer:

Explanation:

To answer this question, we must find the diagonal of a rectangle that isby. Because a rectangle is made up of right angles, the diagonal of a rectangle creates a right triangle with two of the sides.

Because a right triangle is formed by the diagonal, we can use the Pythagorean Theorem, which is:

andeach represent a different leg of the triangle andrepresents the length of the hypotenuse, which in this case is the same as the diagonal length.

我们可以then plug in our known values and solve for

We now must take the square root of each side so that we can solve for

Therefore, the diagonal of the rectangle is.

Example Question #1 :How To Find The Length Of The Diagonal Of A Parallelogram

Parallelogram_12

is a parallelogram. Find the length of diagonal.

Possible Answers:

Correct answer:

Explanation:

To find the length of the diagonal, we can consider only the triangleand use the law of cosines to find the length of the unknown side.

The Law of Cosines:

Whereis the length of the unknown side,andare the lengths of the known sides, andis the angle betweenand.

From the problem:

Example Question #3 :How To Find The Length Of The Diagonal Of A Parallelogram

Parallelogram_13

is a parallelogram. Find the length of diagonal.

Possible Answers:

Correct answer:

Explanation:

To find the length of the diagonal, we can consider only the triangleand use the law of cosines to find the length of the unknown side.

The Law of Cosines:

Whereis the length of the unknown side,andare the lengths of the known sides, andis the angle betweenand.

From the problem:

Example Question #4 :How To Find The Length Of The Diagonal Of A Parallelogram

Parallelogram_15

is a parallelogram. Find the length of diagonal.

Possible Answers:

Correct answer:

Explanation:

To find the length of the diagonal, we can consider only the triangleand use the law of cosines to find the length of the unknown side.

The Law of Cosines:

Whereis the length of the unknown side,andare the lengths of the known sides, andis the angle betweenand.

From the problem:

Example Question #5 :How To Find The Length Of The Diagonal Of A Parallelogram

Parallelogram_16

is a parallelogram. Find the length of diagonal.

Possible Answers:

Correct answer:

Explanation:

To find the length of the diagonal, we can consider only the triangleand use the law of cosines to find the length of the unknown side.

The Law of Cosines:

Whereis the length of the unknown side,andare the lengths of the known sides, andis the angle betweenand.

From the problem:

Example Question #3 :How To Find The Length Of The Diagonal Of A Parallelogram

Parallelogram_14

is a parallelogram. Find the length of diagonal..

Possible Answers:

Correct answer:

Explanation:

To find the length of the diagonal, we can consider only the triangleand use the law of cosines to find the length of the unknown side.

The Law of Cosines:

Whereis the length of the unknown side,andare the lengths of the known sides, andis the angle betweenand.

From the problem:

Example Question #7 :How To Find The Length Of The Diagonal Of A Parallelogram

Parallelogram_17

is a parallelogram. Find the length of diagonal.

Possible Answers:

Correct answer:

Explanation:

To find the length of the diagonal, we can consider only the triangleand use the law of cosines to find the length of the unknown side.

The Law of Cosines:

Whereis the length of the unknown side,andare the lengths of the known sides, andis the angle betweenand.

From the problem:

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