Question

semi perimeter of a triangle cloth piece used to stitch a conical tent is____________ A)10 B)20 C)25 D)15​

Answer 1

Given, an umbrella is made of 12 triangular pieces each of measure 50 cm, 20 cm, 50 cm.

To find area of cloth required we have to first find the area of one piece of cloth.

Semi perimeter, s=

Sum of sides of triangle

-------------------------------------

2

50+20+50

-------------------- = 60

2

Using heron's formula, Area of one triangular piece= √s(s−a)(s−b)(s−c)

= √60(60−50)(60−20)(60−50)

= √60×10×40×10=200√6cm 2

Area of 12 triangular pieces or area of cloth used= Area of one triangular piece × 12

=200√6 cm 2 ×12

=2400√6 cm 2