Question

33. An umbrella is made by stitching ten triangular pieces of cloth, each measuring 25cm, 17cm and 12
cm. Find the cost of total cloth required, if 1cm² costs @ 20.
please answer this question help me...​

Answer 1

The sides of triangular pieces are 20 cm, 50 cm and 50 cm.

Let a = 20 cm, b = 50 cm, c = 50 cm

∴  Semi - perimeter, s = (a + b + c)/2   =  (20 + 50 + 50)/2

s = 60 cm

∴  Area of one triangular piece = root under (√s(s - a)(s - b)(s - c))

=  root under (√60(60 - 20)(60 - 50)(60 - 50))

=   root under (√60 x 40 x 10 x 10)  = 200√6 cm2  

Cloth of each design required = Area of 5 triangular pieces

= 5 x  200√6  = 1000√6 cm2