How to find the length of the diagonal of a quadrilateral - ACT Math
Card 0 of 27

In the parallelogram above, 
 and 
. What is the length of the diagonal 
?

In the parallelogram above,  and 
. What is the length of the diagonal 
?
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, 
. To find 
, we set them equal to one another and solve.



Plugging this value back into both equations, then adding those values together, gives us our answer of 
.
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, . To find 
, we set them equal to one another and solve.
Plugging this value back into both equations, then adding those values together, gives us our answer of .
Compare your answer with the correct one above
A square has a length of 
. What must be the length of the diagonal?
A square has a length of . What must be the length of the diagonal?
A square with a length of 
 indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.


A square with a length of  indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above
If the rectangle has side lengths of 
 and 
, what is the diagonal of the rectangle?
If the rectangle has side lengths of  and 
, what is the diagonal of the rectangle?
Use the Pythagorean Theorem to solve for the diagonal.




Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above

In the parallelogram above, 
 and 
. What is the length of the diagonal 
?

In the parallelogram above,  and 
. What is the length of the diagonal 
?
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, 
. To find 
, we set them equal to one another and solve.



Plugging this value back into both equations, then adding those values together, gives us our answer of 
.
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, . To find 
, we set them equal to one another and solve.
Plugging this value back into both equations, then adding those values together, gives us our answer of .
Compare your answer with the correct one above
A square has a length of 
. What must be the length of the diagonal?
A square has a length of . What must be the length of the diagonal?
A square with a length of 
 indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.


A square with a length of  indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above
If the rectangle has side lengths of 
 and 
, what is the diagonal of the rectangle?
If the rectangle has side lengths of  and 
, what is the diagonal of the rectangle?
Use the Pythagorean Theorem to solve for the diagonal.




Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above

In the parallelogram above, 
 and 
. What is the length of the diagonal 
?

In the parallelogram above,  and 
. What is the length of the diagonal 
?
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, 
. To find 
, we set them equal to one another and solve.



Plugging this value back into both equations, then adding those values together, gives us our answer of 
.
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, . To find 
, we set them equal to one another and solve.
Plugging this value back into both equations, then adding those values together, gives us our answer of .
Compare your answer with the correct one above
A square has a length of 
. What must be the length of the diagonal?
A square has a length of . What must be the length of the diagonal?
A square with a length of 
 indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.


A square with a length of  indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above
If the rectangle has side lengths of 
 and 
, what is the diagonal of the rectangle?
If the rectangle has side lengths of  and 
, what is the diagonal of the rectangle?
Use the Pythagorean Theorem to solve for the diagonal.




Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above

In the parallelogram above, 
 and 
. What is the length of the diagonal 
?

In the parallelogram above,  and 
. What is the length of the diagonal 
?
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, 
. To find 
, we set them equal to one another and solve.



Plugging this value back into both equations, then adding those values together, gives us our answer of 
.
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, . To find 
, we set them equal to one another and solve.
Plugging this value back into both equations, then adding those values together, gives us our answer of .
Compare your answer with the correct one above
A square has a length of 
. What must be the length of the diagonal?
A square has a length of . What must be the length of the diagonal?
A square with a length of 
 indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.


A square with a length of  indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above
If the rectangle has side lengths of 
 and 
, what is the diagonal of the rectangle?
If the rectangle has side lengths of  and 
, what is the diagonal of the rectangle?
Use the Pythagorean Theorem to solve for the diagonal.




Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above

In the parallelogram above, 
 and 
. What is the length of the diagonal 
?

In the parallelogram above,  and 
. What is the length of the diagonal 
?
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, 
. To find 
, we set them equal to one another and solve.



Plugging this value back into both equations, then adding those values together, gives us our answer of 
.
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, . To find 
, we set them equal to one another and solve.
Plugging this value back into both equations, then adding those values together, gives us our answer of .
Compare your answer with the correct one above
A square has a length of 
. What must be the length of the diagonal?
A square has a length of . What must be the length of the diagonal?
A square with a length of 
 indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.


A square with a length of  indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above
If the rectangle has side lengths of 
 and 
, what is the diagonal of the rectangle?
If the rectangle has side lengths of  and 
, what is the diagonal of the rectangle?
Use the Pythagorean Theorem to solve for the diagonal.




Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above

In the parallelogram above, 
 and 
. What is the length of the diagonal 
?

In the parallelogram above,  and 
. What is the length of the diagonal 
?
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, 
. To find 
, we set them equal to one another and solve.



Plugging this value back into both equations, then adding those values together, gives us our answer of 
.
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, . To find 
, we set them equal to one another and solve.
Plugging this value back into both equations, then adding those values together, gives us our answer of .
Compare your answer with the correct one above
A square has a length of 
. What must be the length of the diagonal?
A square has a length of . What must be the length of the diagonal?
A square with a length of 
 indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.


A square with a length of  indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above
If the rectangle has side lengths of 
 and 
, what is the diagonal of the rectangle?
If the rectangle has side lengths of  and 
, what is the diagonal of the rectangle?
Use the Pythagorean Theorem to solve for the diagonal.




Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above

In the parallelogram above, 
 and 
. What is the length of the diagonal 
?

In the parallelogram above,  and 
. What is the length of the diagonal 
?
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, 
. To find 
, we set them equal to one another and solve.



Plugging this value back into both equations, then adding those values together, gives us our answer of 
.
In a parallelogram, the two diagonals bisect each other at their centers. Therefore, . To find 
, we set them equal to one another and solve.
Plugging this value back into both equations, then adding those values together, gives us our answer of .
Compare your answer with the correct one above
A square has a length of 
. What must be the length of the diagonal?
A square has a length of . What must be the length of the diagonal?
A square with a length of 
 indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.


A square with a length of  indicates that all sides are 
 since a square has 4 equal sides. Use the Pythagorean Theorem to solve for the diagonal.
Compare your answer with the correct one above