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Question
A hand fan is made by stitching lo equal size triangular strips of two different types of paper as shown in Fig. 12.28. The dimensions of equal strips are 25 cm, 25 cm and 14 cm. Find the area of each type of paper needed to make the hand fan.
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Solution
Given that the sides of ΔAOB are
AO = 24 cm
OB = 25 cm
BA = 14 cm
Area of each equal strips = Area of Δle AOB
Now, for area of ΔAOB
Perimeter of ΔAOB
Let 2s = AO + OB + BA
`⇒s=1/2(AO+OB+BA)`
`=1/2(25-25-14)=32 cm`
∴๐ต๐ฆ ๐ข๐ ๐๐๐ ๐ป๐๐๐๐′๐ ๐๐๐๐๐ข๐๐๐
๐ด๐๐๐ ๐๐ (Δ๐ด๐๐ต)=`sqrt(s(s-ao(s-ob)s-ba))`
`=sqrt(32(32-25)(32-25)(32-14))`
`=sqrt(32(7)(4)(18))`
`=168 cm^2`
∴ Area of each type of paper needed to make the hand fan = 5 ×(๐๐๐๐ ๐๐ Δ๐ด๐๐ต)
= 5 × 168
= `840 cm^2`
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