### All GRE Math Resources

## Example Questions

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

The diagram above represents a square ABCD with a semi-circle directly attached to its side. If the area of the figure is 16 + 2π, what is its outer perimeter?

**Possible Answers:**

12 + 2π

16

None of the other answers

20π

16 + 2π

**Correct answer:**

12 + 2π

We know that our area can be represented by the following equation:

Instead of solving the algebra, you should immediately note several things. 16 = 4^{2} and 4 = 2^{2}. If the side of the square is 4, then s = 4 would work out as:

which is just what we need.

With s = 4, we know that 3 sides of our figure will have a perimeter of 12. The remaining semicircle will be one half of the circumference of a circle with diameter of 4; therefore it will be 0.5 * 4 * π or 2π.

Therefore, the outer perimeter of our figure is 12 + 2π.

### Example Question #171 : Plane Geometry

A square table has an area of square centimeters and a perimeter of centimeters.

If , what is the perimeter of the square?

**Possible Answers:**

**Correct answer:**

We start by writing the equations for the area and perimeter in terms of a side of length s.

Then, substitute both of these expressions into the given equation to solve for side length.

Finally, since four sides make up the perimeter, we substitue s back into our perimeter equation and solve for P.

### Example Question #5 : How To Find The Perimeter Of A Square

The diagonal of square is feet. Approximately how long in inches is the perimeter of square ?

**Possible Answers:**

**Correct answer:**

First we must convert to inches.

The diagonal of a square divides the square into two isosceles-right triangles. Using the Pythagorean Theorem, we know that , where x is equal to the length of one side of the square.

This gives us .

Therefore, the perimeter of square is equal to .

### Example Question #1 : Squares

In the figure above, the circle is inscribed within the bounding square. If r = 5, what is the area of the shaded region?

**Possible Answers:**

25 - (25/4)π

25π

100

100π

100 - 25π

**Correct answer:**

25 - (25/4)π

In order to solve this, we must first find the area of the containing square and then remove the inscribed circle. Once this is done, we need to divide our result by 4 in order to get the one-forth that is the one shaded region.

One side of the square will be equal to the circle's diameter (2r). Since r = 5, d = 10. Therefore, the area of the square is d^{2} = 10^{2} = 100. The area of the circle is πr^{2} = 5^{2}π = 25π.

Therefore, the area of the four "corner regions" is equal to 100 - 25π. One of these is equal to (100 - 25π) / 4. Simplified, this is 25 - (25/4)π.

### Example Question #1361 : Gre Quantitative Reasoning

Find the area of a square with a side length of 4.

**Possible Answers:**

32

24

16

8

**Correct answer:**

16

All sides are equal in a square. To find the area of a square, multiply length times width. We know length = 4 but since all sides are equal, the width is also 4. 4 * 4 = 16.

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

If one doubles the radius of the semi-circle on the right of the diagram above, by what percentage does the overall area of the diagram change?

**Possible Answers:**

400%

200%

150%

100%

300%

**Correct answer:**

300%

To compare, first calculate the area of figure 1. Since it shares dimensions with the semi-circle, we will put all our variables in terms of the radius of that semi-circle:

A_{1} = (2r)^{2} + πr^{2}/2 = 4r^{2} + πr^{2}/2 = r^{2}(4 + π)/2

If we double r, we get:

A_{2} = (2 * 2r)^{2} + π(2r)^{2}/2 = 16r^{2} + π4r^{2}/2 = 4r^{2}(4 + π)/2

This means that the new figure is 4x the size of the original. This is an increase of 300%.

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

100 cm = 1 m

Quantity A: The area of a square with side 1 m

Quantity B: One hundred times the area of a square with side 1 cm

**Possible Answers:**

Quantity A is greater.

The two quantities are equal.

Quantity B is greater.

The relationship cannot be determined from the information given.

**Correct answer:**

Quantity A is greater.

The obvious answer for this problem is that they are equal. Remember quantitative comparisons are often tricky and require you to check your initial inclination. If 1 m equals 100 cm then a square with side 1 m (100 cm) has an area of 100 cm x 100 cm or 10,000 cm^{2}. The area of a square with a 1 cm side is 1 cm x 1 cm or 1 cm^{2}. One hundred times 1 cm^{2 }is 100 cm^{2}. 10,000 cm^{2} is larger than 100 cm^{2} so Quantity A is greater.

### Example Question #2 : Squares

A square is inscribed in a circle. The diameter of the circle is 10 feet. What is the area of the square?

**Possible Answers:**

It cannot be determined from the information provided.

**Correct answer:**

Since the diameter of the circle is 10, we know the radius of the circle is 5 feet. We can then draw radii that go from the center to two consecutive corners of the square. These radii are both 5 feet, and form a 90 degree angle (since they are diagonals of a square). Thus, with the enclosed side of the square they form a 45-45-90 triangle. Thus, the side of the square must be (this can also be found with the Pythagorean theorem). Then, the area of the square is

### Example Question #6 : How To Find The Area Of A Square

In the figure above, a square is inscribed in a circle with a diameter of 5 cm.

What is the area of the square?

**Possible Answers:**

**Correct answer:**

The diameter of the circle and the sides of the square form a 45-45-90 triangle. Since the hypotenuse is 5 cm, then a leg of the triangle (a side of the square) is .

The area of the square is then .

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

Square is on a coordinate plane, and each side of the square is parallel to either the -axis or -axis. Point has the coordinate and Point has the coordinate .

Quantity A: The area of square

Quantity B: 24

**Possible Answers:**

Quantity A is greater

The two quantities are equal

The information cannot be determined based on the information provided

Quantity B is greater

**Correct answer:**

Quantity A is greater

If you draw points and on the coordinate plane, you know that they are opposite ends of the square, since the sides are parallel to the axes. This means that the squares have sides with lengths of 5, making the area 25.