All ACT Math Resources
Example Questions
Example Question #1 : How To Find The Length Of The Side Of A Parallelogram
is a parallelogram with an area of . Find .
There is insufficient information to solve the problem.
In order to find , we must first find . The formula for the area of a parallelogram is:
We are given as the area and as the base.
Now, we can use trigonometry to solve for . With respect to , we know the opposite side of the right triangle and we are looking for the hypotenuse. Thus, we can use the sine function.
Example Question #91 : Quadrilaterals
A parallelogram, with dimensions in cm, is shown below.
What is the perimeter of the parallelogram, in cm?
The triangle on the left side of the figure has a and a angle. Since all of the angles of a triangle must add up to , we can find the angle measure of the third angle:
Our third angle is and we have a triangle.
A triangle has sides that are in the corresponding ratio of . In this case, the side opposite our angle is , so
We also now know that
Now we know all of our missing side lengths. The right and left side of the parallelogram will each be . The bottom and top will each be . Let's combine them to find the perimeter:
Example Question #1 : How To Find The Perimeter Of A Parallelogram
Note: Figure NOT drawn to scale.
Give the perimeter of Parallelogram in the above diagram.
By the 30-60-90 Theorem, the length of the short leg of is the length of the long leg divided by , so
Its hypotenuse has twice the length of the short leg, so
The perimeter of the parallelogram is
Example Question #331 : Act Math
Note: Figure NOT drawn to scale.
Give the perimeter of Parallelogram in the above diagram.
By the 45-45-90 Theorem, the lengths of the legs of are equal, so
Its hypotenuse has measure that of the common measure of its legs, so
The perimeter of the parallelogram is
Example Question #2 : How To Find The Perimeter Of A Parallelogram
Note: Figure NOT drawn to scale.
To the nearest tenth, give the perimeter of Parallelogram in the above diagram.
The perimeter of the parallelogram is
Example Question #333 : Act Math
In the above figure, Parallelogram has area 100. To the nearest tenth, what is its perimeter?
By the 45-45-90 Theorem, . Since and are its base and height:
Also by the 45-45-90 Theorem,
The perimeter of the parallelogram is
Example Question #334 : Act Math
In the above figure, Parallelogram has area 100. To the nearest tenth, what is its perimeter?
By the 30-60-90 Theorem,
The area of the parallelogram is the product of height and base , so
Also by the 30-60-90 Theorem,
The perimeter of the parallelogram is
Example Question #335 : Act Math
Note: Figure NOT drawn to scale.
In the above figure, Parallelogram has area 100. To the nearest tenth, what is its perimeter?
The area of the parallelogram is the product of height and base , so
The perimeter of the parallelogram is
Example Question #1 : How To Find The Length Of The Diagonal Of A Parallelogram
If a rectangular plot measures by , what is the length of the diagonal of the plot, in feet?
To answer this question, we must find the diagonal of a rectangle that is by . 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:
and each represent a different leg of the triangle and represents the length of the hypotenuse, which in this case is the same as the diagonal length.
We can 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 #2 : How To Find The Length Of The Diagonal Of A Parallelogram
is a parallelogram. Find the length of diagonal .
To find the length of the diagonal, we can consider only the triangle and use the law of cosines to find the length of the unknown side.
The Law of Cosines:
Where is the length of the unknown side, and are the lengths of the known sides, and is the angle between and .
From the problem: