If a square had a perimeter of 20cm, find the length of the diagonal. round to the nearest tenth.

The lenght of the diagonal is 7.1cm

Step-by-step explanation:

First we have to calculate how much each side of the square measures

p = perimeter = 20cm

s = side

p = 4 * s

we replace with the known values

20cm = 4 * s

20cm / 4 = s

5cm = s

Each side of the square measures 5cm

To calculate one side of a right triangle from the other 2 sides we have to use Pythagoras

h = hypotenuse

a = leg 1 = 5cm

b = leg 2 = 5cm

h² = a² + b²

we replace the known values

h² = (5cm) ² + (5cm) ²

h² = 25cm² + 25cm²

h² = 50cm²

h = √ (50cm²)

h = 7.07cm

Round to the nearest tenth

h = 7.07cm = 7.1cm

The length of the hypotenuse is 7.1cm

The hypotenuse of the triangle is the diagonal of the square