All PSAT Math Resources
Example Questions
Example Question #21 : Quadrilaterals
A half circle has an area of . What is the area of a square with sides that measure the same length as the diameter of the half circle?
144
36
108
81
72
144
If the area of the half circle is , then the area of a full circle is twice that, or .
Use the formula for the area of a circle to solve for the radius:
36π = πr2
r = 6
If the radius is 6, then the diameter is 12. We know that the sides of the square are the same length as the diameter, so each side has length 12.
Therefore the area of the square is 12 x 12 = 144.
Example Question #1 : How To Find The Length Of The Side Of A Square
The area of square R is 12 times the area of square T. If the area of square R is 48, what is the length of one side of square T?
4
2
1
16
2
We start by dividing the area of square R (48) by 12, to come up with the area of square T, 4. Then take the square root of the area to get the length of one side, giving us 2.
Example Question #1 : How To Find The Length Of The Side Of A Square
When the side of a certain square is increased by 2 inches, the area of the resulting square is 64 sq. inches greater than the original square. What is the length of the side of the original square, in inches?
17
15
18
16
14
15
Let x represent the length of the original square in inches. Thus the area of the original square is x2. Two inches are added to x, which is represented by x+2. The area of the resulting square is (x+2)2. We are given that the new square is 64 sq. inches greater than the original. Therefore we can write the algebraic expression:
x2 + 64 = (x+2)2
FOIL the right side of the equation.
x2 + 64 = x2 + 4x + 4
Subtract x2 from both sides and then continue with the alegbra.
64 = 4x + 4
64 = 4(x + 1)
16 = x + 1
15 = x
Therefore, the length of the original square is 15 inches.
If you plug in the answer choices, you would need to add 2 inches to the value of the answer choice and then take the difference of two squares. The choice with 15 would be correct because 172 -152 = 64.
Example Question #622 : Geometry
If the area of a square is 25 inches squared, what is the perimeter?
10
Not enough information
20
15
25
20
The area of a square is equal to length times width or length squared (since length and width are equal on a square). Therefore, the length of one side is or The perimeter of a square is the sum of the length of all 4 sides or
Example Question #201 : Plane Geometry
What is the length of the diagonal of a rectangle that is 3 feet long and 4 feet wide?
The diagonal of the rectangle is equivalent to finding the length of the hypotenuse of a right triangle with sides 3 and 4. Using the Pythagorean Theorem:
Therefore the diagonal of the rectangle is 5 feet.
Example Question #202 : Plane Geometry
The length and width of a rectangle are in the ratio of 3:4. If the rectangle has an area of 108 square centimeters, what is the length of the diagonal?
12 centimeters
18 centimeters
9 centimeters
15 centimeters
24 centimeters
15 centimeters
The length and width of the rectangle are in a ratio of 3:4, so the sides can be written as 3x and 4x.
We also know the area, so we write an equation and solve for x:
(3x)(4x) = 12x2 = 108.
x2 = 9
x = 3
Now we can recalculate the length and the width:
length = 3x = 3(3) = 9 centimeters
width = 4x = 4(3) = 12 centimeters
Using the Pythagorean Theorem we can find the diagonal, c:
length2 + width2 = c2
92 + 122 = c2
81 + 144 = c2
225 = c2
c = 15 centimeters
Example Question #1 : Rectangles
The two rectangles shown below are similar. What is the length of EF?
8
6
5
10
10
When two polygons are similar, the lengths of their corresponding sides are proportional to each other. In this diagram, AC and EG are corresponding sides and AB and EF are corresponding sides.
To solve this question, you can therefore write a proportion:
AC/EG = AB/EF ≥ 3/6 = 5/EF
From this proportion, we know that side EF is equal to 10.
Example Question #1 : How To Find The Length Of The Side Of A Rectangle
A rectangle is x inches long and 3x inches wide. If the area of the rectangle is 108, what is the value of x?
3
4
6
12
8
6
Solve for x
Area of a rectangle A = lw = x(3x) = 3x2 = 108
x2 = 36
x = 6
Example Question #1 : How To Find The Length Of The Side Of A Rectangle
If the area of rectangle is 52 meters squared and the perimeter of the same rectangle is 34 meters. What is the length of the larger side of the rectangle if the sides are integers?
14 meters
15 meters
16 meters
12 meters
13 meters
13 meters
Area of a rectangle is = lw
Perimeter = 2(l+w)
We are given 34 = 2(l+w) or 17 = (l+w)
possible combinations of l + w
are 1+16, 2+15, 3+14, 4+13... ect
We are also given the area of the rectangle is 52 meters squared.
Do any of the above combinations when multiplied together= 52 meters squared? yes 4x13 = 52
Therefore the longest side of the rectangle is 13 meters
Example Question #1 : How To Find If Rectangles Are Similar
Note: Figure NOT drawn to scale.
In the above figure,
.
.
Give the perimeter of .
We can use the Pythagorean Theorem to find :
The similarity ratio of to is
so multiplied by the length of a side of is the length of the corresponding side of . We can subsequently multiply the perimeter of the former by to get that of the latter:
Certified Tutor