ACT Math : Plane Geometry

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #1 : How To Find The Perimeter Of A Square

A square garden has an area of 64 square feet. If you add 3 feet to each side, what is the new perimeter of the garden?

Possible Answers:

32

25

121

20

44

Correct answer:

44

Explanation:

By finding the square root of the area of the garden, you find the length of one side, which is 8. We add 3 feet to this, giving us 11, then multiply this by 4 to get 44 feet for the perimeter.

Example Question #1 : How To Find The Perimeter Of A Square

The area of the shaded region of a square is 18. What is the perimeter of the square?

Possible Answers:

24

36

28

20

Correct answer:

24

Explanation:

The area of the shaded region, which covers half of the square is 18 meaning that the total area of the square is 18 x 2, or 36. The area of a square is equal to the length of one side squared. Since the square root of 36 is 6, the length of 1 side is 6. The perimeter is the length of 1 side times 4 or 6 x 4.

Example Question #851 : Basic Geometry

The area of a square is .  If the square is enlarged by a factor of 2, what is the perimeter of the new square?

Possible Answers:

Correct answer:

Explanation:

The area of a square is given by  so we know the side is 5 cm.  Enlarging by a factor of two makes the new side 10 cm.  The perimeter is given by , so the perimeter of the new square is 40 cm.

Example Question #161 : Quadrilaterals

The diagonal of a square has a length of 10 inches. What is the perimeter of the square in inches squared?

Possible Answers:

Correct answer:

Explanation:

Using the Pythagorean Theorem, we can find the edge of a side to be √50, by 2a2=102. This can be reduced to 5√2. This can then be multiplied by 4 to find the perimeter. 

Example Question #401 : Geometry

What is the perimeter of a square with an area of ?

Possible Answers:

Correct answer:

Explanation:

1. Find the side lengths:

 

2. Use the side lengths to find the perimeter:

Example Question #1 : How To Find The Perimeter Of A Square

Find the perimeter of a square whose area is .

Possible Answers:

Correct answer:

Explanation:

To solve, you must first find the side length.

Then, you must multiply the side length by 4 since there are 4 sides. Thus,

In this case, volume and perimeter were the same numerical value, but this won't always be the case.

Example Question #1 : How To Find The Perimeter Of A Square

Find the perimeter of a square with side length .

Possible Answers:

Correct answer:

Explanation:

To find perimeter, simply multiply side length by . Thus,

Example Question #171 : Quadrilaterals

The area of a square is , what is the perimeter of the square?

Possible Answers:

Correct answer:

Explanation:

Since the sides of a square are all the same, the area of a square can be found by  Therefore, the side of the square must be  The perimeter of a square can be found by adding up all of the four sides:  

Example Question #3 : How To Find The Length Of The Side Of A Square

If the area of the square is 100 square units, what is, in units, the length of one side of the square?

Possible Answers:

Correct answer:

Explanation:

Example Question #1 : How To Find The Length Of The Side Of A Square

In Square . Evaluate  in terms of .

Possible Answers:

Correct answer:

Explanation:

If diagonal  of Square  is constructed, then  is a 45-45-90 triangle with hypotenuse . By the 45-45-90 Theorem, the sidelength  can be calculated as follows:

.

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