Question

Areas
17. An umbrella is made by stitching 12
triangular pieces of cloth, each measuring
(50 cm x 20 cm x 50 cm). Find the area of
the cloth used in it.
​

Answer 1

${\purple{\bf{Hola!!}}}$

Given:-

Measurements of 1 triangular piece=50×20×50cm

To find:-

Cloth used to make the umbrella i.e.

Area of one triangle × 12

Area of ∆ = ${\sqrt{s(s-a)(s-b)(s-c)}}$

where a,b & c are the sides and

s=${\frac{a+b+c}{2}}$

s=${\frac{50+50+20}{2}}$

s=60 cm

Area=${\sqrt{60(60-50)(60-50)(60-20)}}$

Area=${\sqrt{60×10×10×40}}$

A=${\sqrt{2×5×3×2×10×10×4×5×2}}$

A=2×5×10${\sqrt{4×3×2}}$

Area=100${\sqrt{24}}$cm²

Cloth required=100√24×12

=(100×4.89 cm²)12

=489 cm² ×12

${\bf{\blue{Cloth\: required=5868\:cm^2}}}$