Since the area is 25 square meters and we know it's a square, the length of each side is 5 meters, since 5 x 5 = 25.

To find the length of the diagonal, use the Pythagorean theorem:

To solve, use the Pythagorean Theorem:

A square is shown below with its diagonal.

Each of the triangles formed is an isosceles right triangle with congruent legs - by the 45-45-90 Triangle Theorem, they are 45-45-90 triangles. Also by the 45-45-90 Triangle Theorem, the diagonal, the hypotenuse of each triangle, measures  times the length of a leg. Since each side of the square measures 1, the diagonal has length , not  .

Recall that the side lengths of a square are each congruent; recall further that the angles in a square are each right angles. Hence, the diagonal  of the square  may be considered the hypotenuse of a right isosceles triangle whose other two sides are  and . The side lengths of  and  are given as  units; hence, we can deduce the diagonal  of the square  by the Pythagorean Theorem, as shown:

.

Hence, the length of the diagonal  of the square  is  units.

Squares have four congruent sides. If one side is 12, the other sides must be as well. Since the diagonal makes a right triangle with the other sides we can use Pythagorean theorem to find the diagonal. 

Take the square root of both sides:

The length of the diagonal is 17 inches.

The formula for the area of a square is

where  is the length of the sides. So the solution can be found by

Since  is a square, the side  is the same length as all of the other three sides.

We get area by multiplying length by width (or base by height, if you prefer), since all sides are equal, it looks like this:

Don't forget, the units are SQUARE INCHES.

Square ABCD contains both the red and green shapes. The red shape is equal to the area of one-fourth of the circle. Finding the area of square ABCD and subtracting only the area of the red shape will give the area of only the green shape.

Since ABCD is a square, angle BAC is a right angle that sits at the center of the circle (point A). Since a right angle is 90^o and a circle is 360^o, the red shape's area must be one quarter (or ) of the entire circle's area. Use the equation  to find the area of the entire circle, then multiply this by  to find the area of only the red shape.

Subtracting this from the area of the square gives the area of the green area outside of the circle.

We need to find the length of the side of the square in order to find the area. The diagonal makes two triangles with the sides of the square. Using the special triangle ratio of , we know that if the hypotenuse is then the length of each side must be . The area of the square is .

To find the area of a square, you only need to know one side. The length of one side squared is the area.