Question

Side of a square is $5$ $cm.$ What is the length of its diagonal.

Answer 1

A diagonal divides the square into two congruent right triangles, thus you can use the side of the square to find the length of the diagonal ( which would be the hypotenuse of the right angled triangle).

If the square has the side of s cm then ,

by using pythagorean theorem,

(diagonal)^2 = (side)^2 + (side)^2

which gives

diagonal = (side) X sqrt(2)

here

side = 5 cm therefore,

diagonal = 5 x sqrt(2)

= 5 x 0.707

= 7.07 cm