#### 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.

#### 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`

∴π΅π¦ π’π πππ π»ππππ′π πππππ’πππ

π΄πππ ππ (Δπ΄ππ΅)=`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 ×(ππππ ππ Δπ΄ππ΅)

= 5 × 168

= `840 cm^2`