Instruction

1

Divide the rectangle by a diagonal into two equal triangles. In this case, the diagonal will be the hypotenuse of these triangles. And, as we know from the Pythagorean theorem, the hypotenuse squared is equal to the sum of the squares of the legs.

So, for finding the diagonal of a rectangle need:

find the sum of the squares of the sides of the rectangle A2 + b2, where a and b are the lengths of the sides of the rectangle;

extract from the result the square root.

Example:

Determine the length of the diagonal of rectangle with sides 3 and 4, see

Find the sum of the squares of the sides of the rectangle 32 + 42 = 9 + 16 = 25.

Extract from the result the square root of the diagonal length equal to 5 cm.

So, for finding the diagonal of a rectangle need:

find the sum of the squares of the sides of the rectangle A2 + b2, where a and b are the lengths of the sides of the rectangle;

extract from the result the square root.

Example:

Determine the length of the diagonal of rectangle with sides 3 and 4, see

Find the sum of the squares of the sides of the rectangle 32 + 42 = 9 + 16 = 25.

Extract from the result the square root of the diagonal length equal to 5 cm.

Note

The diagonals of a rectangle are equal. If the found length one, the length of the second will be exactly the same.