What is the formula to find out the diagnal length of a square or rectangle?

Question

What is the formula to find out the diagnal length of a square or rectangle?

Answer 1

You use pythagorases theorem, which lets you work out the side of a triangle if you are given two of the other sides and the triangle is right angled.

As it's a square or a rectangle it must have the right angle.

The forumla is:

a^2+b^2=c^2

So, let's call two sides of the square/rectangle a and b (if it's a square, a=b as all sides of a square are equal) and then the dignol is c.

So just say you had  a rectangle with two sides distance 3 and two sides distance 4. a=3, b=4, c=?

3^2 + 4^2 = c^2

9 + 16 = c^2

            = 25.

As this is c squared, you must square root the number. The square root of c is 5, so the diagnol is 5.

I have here a small picture of the theory to help you visualise it, they've just replaced c with h as the name of that side is the hypotenuse.

http://www.enchantedlearning.com/math/gi...

Hope this helped!

Answer 2

c^2 = a^2 + b^2

(sqrt)c^2 = c or diagonal length

Answer 3

well for a square you halve it (so that its an equilateral triangle) and then use pi to find out the diagonal length

to do pi use this formula

c (being the diagonal side) = b squared + c squared

(a and b are the other two sides)

i couldnt find the little 2 for the square symbol

hope this helps