If the length and breadth of a rectangle are 10cm and 20cm respectively, find the length of its diagonal

L = 10

B = 20

so to find the diagonal you have to use Pythagorean theorem that is a^2 + b^2 = c^2

10^2 + 20^2 = X^2

X = root of 10^2 + 20^2

X = root of 100 + 400

X = root of 500

X = appox 22.36

22.4 cm

Step-by-step explanation:

First draw the rectangle and divide it into two triangles.

Take one triangle out and with the length and breath solve for the hypotenuse using Pythagoras theorem

.: H^2 = 10^2 + 20^2

H^2 = 500

Find the square root of both sides of the equation

H = 22.4 cm = the length of the diagonal

it would open into a square depending on the type of envelope i’m not sure about the second part