Geometry - Quadrilaterals

Find the area of a square if it has a diagonal of $\sqrt5$ .

$\frac{5}{2}$

$\frac{15}{2}$

$5\sqrt2$

Explanation

The diagonal of a square is also the hypotenuse of a triangle.

Recall how to find the area of a square:

$\text{Area}=\text{side}^2$

Now, use the Pythagorean theorem to find the area of the square.

$\text{side}^2+\text{side}^2=\text{Diagonal}^2$

$2(\text{side})^2=\text{Diagonal}^2$

$\text{side}^2=\frac{\text{Diagonal}^2}{2}$

$\text{Area}=\text{side}^2=\frac{\text{Diagonal}^2}{2}$

Substitute in the length of the diagonal to find the area of the square.

$\text{Area}=\frac{(\sqrt5)^2}{2}$

Simplify.

$\text{Area}=\frac{5}{2}$

The perimeter of a square is 48. What is the length of its diagonal?

$12\sqrt{2}$

$\sqrt{12}$

$24\sqrt{2}$

$48\sqrt{2}$

$2\sqrt{12}$

Explanation

Perimeter = side * 4

48 = side * 4

Side = 12

We can break up the square into two equal right triangles. The diagonal of the sqaure is then the hypotenuse of these two triangles.

Therefore, we can use the Pythagorean Theorem to solve for the diagonal:

$\sqrt{144+144}=\sqrt{hypotenuse^2}$

$hypotenuse=\sqrt{2\times 144}=\sqrt{2\times 12\times 12}=12\sqrt{2}$

In the trapezoid below, find the degree measure of .

$76^\circ$

$86^\circ$

$153^\circ$

$93^\circ$

Explanation

In a trapezoid, the angles on the same leg (called adjacent angles) are supplementary, meaning they add up to degrees.

and the angle measuring degrees are adjacent angles that are supplementary.

An isosceles trapezoid has two bases that are parallel to each other. The larger base is times greater than the smaller base. The smaller base has a length of inches and the length of non-parallel sides of the trapezoid have a length of inches.

What is the perimeter of the trapezoid?

Explanation

To find the perimeter of this trapezoid, first find the length of the larger base. Then, find the sum of all of the sides. It's important to note that since this is an isosceles trapezoid, both of the non-parallel sides will have the same length.

The solution is:

The smaller base is equal to inches. Thus, the larger base is equal to:

$2.5\times4=10$

, where the length of one of the non-parallel sides of the isosceles trapezoid.

$P=2.5+10+(2\times 4.5)$

Find the length of a side of a rhombus if it has diagonals possessing the following lengths: and .

$\sqrt5$

$\sqrt6$

$\sqrt2$

Cannot be determined

Explanation

Recall that the diagonals of a rhombus bisect each other and are perpendicular to one another.

In order to find the length of the side, we can use Pythagorean's theorem. The lengths of half of the diagonals are the legs, and the length of the side of the rhombus is the hypotenuse.

First, find the lengths of half of the diagonals.

$\frac{\text{Diagonal 1}}{2}=\frac{2}{2}=1$

$\frac{\text{Diagonal 2}}{2}=\frac{4}{2}=2$

Next, substitute these half diagonals as the legs in a right triangle using the Pythagorean theorem.

$1^2+2^2=\text{side length}^2$

$\text{side length}^2=1+4=5$

$\text{side length}=\sqrt5$

If the diagonal of a square is $19\sqrt2$ , what is the area of the square?

Explanation

The diagonal of a square is also the hypotenuse of a triangle whose legs are the sides of the square.

Thus, from knowing the length of the diagonal, we can use Pythagorean's Theorem to figure out the side lengths of the square.

$\text{Diagonal}^2=\text{side length}^2+\text{side length}^2$

$\text{Diagonal}^2=2(\text{side length})^2$

$(\text{side length})^2=\frac{\text{Diagonal}^2}{2}$

$\text{side length}=\frac{\text{Diagonal}}{\sqrt2}$

We can now find the side length of the square in question.

$\text{side length}=\frac{19\sqrt2}{\sqrt2}$

Simplify.

$\text{side length}=19$

Now, recall how to find the area of a square:

$\text{Area}=(\text{side length})^2$

For the square in question,

$\text{Area }=19 ^2$

Solve.

$\text{Area }=361$

If the diagonal of a square is $6\sqrt2$ , what is the area of the square?

Explanation

The diagonal of a square is also the hypotenuse of a right triangle that has the side lengths of the square as its legs.

We can then use the Pythgorean Theorem to write the following equations:

$\text{Diagonal}=\sqrt{\text{side length}^2+\text{side length}^2}$

$\text{Diagonal}=\sqrt{2(\text{side length})^2}$

$\text{Diagonal}=(\text{side length})\sqrt2$

$\text{Side length}=\frac{\text{Diagonal}}{\sqrt2}$

Now, use this formula and substitute using the given values to find the side length of the square.

$\text{Side length}=\frac{6\sqrt2}{\sqrt2}$

Simplify.

$\text{Side length}=6$

Now, recall how to find the area of a square.

$\text{Area}=(\text{side length})^2$

For this square in question,

$\text{Area}=6^2$

Solve.

$\text{Area}=36$

In the figure, a square is inscribed in a circle. If the perimeter of the square is , then what is the area of the shaded region?

Explanation

From the figure, you should notice that the diameter of the circle is also the diagonal of the square.

In order to find the area of the shaded region, we will first need to find the area of the circle and the area of the square.

First, let's find the area of the square.

From the given information, we can find the length of a side of the square.

$\text{Perimeter}=4(\text{side})$

$\text{side}=\frac{\text{Perimeter}}{4}$

Substitute in the value of the perimeter to find the length of a side of the square.

$\text{side}=\frac{8}{4}$

Simplify.

$\text{side}=2$

Now recall how to find the area of a square:

$\text{Area of square}=\text{side}^2$

Substitute in the value of the side of the square to find the area.

$\text{Area of square}=2^2$

Simplify.

$\text{Area of square}=4$

Now, use the Pythagorean theorem to find the length of the diagonal of the square.

$\text{Diagonal}^2=\text{side}^2+\text{side}^2$

$\text{Diagonal}=\sqrt{2(\text{side})^2}$

Simplify.

$\text{Diagonal}=\text{side}\sqrt2$

Substitute in the value of the side of the square to find the length of the diagonal.

$\text{Diagonal}=2\sqrt2$

Recall that the diagonal of the square is the same as the diameter of the circle.

$\text{Diameter}=\text{Diagonal}=2\sqrt2$

From the diameter, we can then find the radius of the circle:

$\text{Radius}=\frac{\text{Diameter}}{2}$

$\text{Radius}=\frac{2\sqrt2}{2}$

Simplify.

$\text{Radius}=\sqrt2$

Now, use the radius to find the area of the circle.

$\text{Area of Circle}=\pi\times\text{radius}^2$

$\text{Area of circle}=\pi\times (\sqrt2)^2$

Simplify.

$\text{Area of circle}=2\pi$

To find the area of the shaded region, subtract the area of the square from the area of the circle.

$\text{Area of Shaded Region}=\text{Area of circle}-\text{Area of square}$

$\text{Area of shaded region}=2\pi-4$

Solve.

$\text{Area of shaded region}=2.28$

Given that a rhombus has a perimeter of , find the length of one side of the rhombus.

Explanation

The perimeter of a rhombus is equal to , where the length of one side of the rhombus.

Since , we can set up the following equation and solve for .

$124=4\times (S)$

$S=\frac{124}{4}=31$

A kite has a perimeter of inches. One pair of adjacent sides of the kite have a length of inches. What is the measurement for each of the other two sides of the kite?