How to find a diagonal in a rectangle

How to find a diagonal in a rectangle

Rectangle – a flat geometrical figure. The rectangle is a quadrangle, at which all right angles. How to find a square diagonal if lengths of its parties are known?

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Instruction

1

Let's divide a rectangle a diagonal into two equal triangles. In this case the diagonal will be a hypotenuse of these triangles. And, as it is known from Pythagorean theorem, the square of a hypotenuse is equal to the sum of squares of legs.
So, it is necessary for search of a diagonal of a rectangle:
to find the sum of squares of the parties of a rectangle a2 + b2, where and and b – lengths of the parties of a rectangle;
to take a square root from the received result.
Example:
Let's determine rectangle diagonal length with the parties of 3 and 4 cm.
We find the sum of squares of the parties of a rectangle 32 + 42 = 9 + 16 = 25.
To take a square root from the received result – length of a diagonal is equal 5 cm.