An umbrella is made by stitching 10 triangular pieces of clothes of 2 different colors, each piece measuring 9 cm, 40 cm and 41 cm. how much clothes is required for the umbrella? if the cost of 1 cm square cloth is rs. 0.25, find the total cost of the clothes.

See below in bold.

Step-by-step explanation:

The triangular piece of cloth is a right triangle because 41^2 = 40^2 + 9^2 (By the Pythagoras theorem).

So the area of one piece = 1/2 * 9 * 40  cm^2.

The total amount of cloth  required for one umbrella = 10 * 1/2 * 9 * 40

= 1800 cm^2.

The total cost =  1800 * 0.25 = Rs 450.