The area of an equilateral triangle ABC is 17320.5 cm2. With each vertex of the triangle as centre, a circle is drawn with radius equal to half the length of the side of the triangle (see Fig. 12.28). Find the area of the shaded region. (Use π = 3.14 and $$\sqrt{3}$$ = 1.73205)

Asked by Pragya Singh | 1 year ago |  102

##### Solution :-

ABC is an equilateral triangle.

∠ A = ∠ B = ∠ C = 60°

There are three sectors each making 60°.

Area of ΔABC = 17320.5 cm2

⇒ $$\dfrac{\sqrt{3}}{4}$$ ×(side)2 = 17320.5

⇒ (side)2 = $$17320.5×\dfrac{4}{1.73205}$$

⇒ (side)2 = 4×104

⇒ side = 200 cm

Radius of the circles = $$\dfrac{ 200}{2}$$ cm = 100 cm

Area of the sector = ($$\dfrac{ 60°}{360°}$$)×πrcm2

= $$\dfrac{1}{6}$$×3.14×(100)cm2

= $$\dfrac{ 15700}{3}$$cm2

Area of 3 sectors = 3×$$\dfrac{ 15700}{3}$$ = 15700 cm2

Thus, area of the shaded region

= Area of equilateral triangle ABC – Area of 3 sectors

= 17320.5-15700 cm= 1620.5 cm2

Answered by Abhisek | 1 year ago

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