ক্ষেত্রফল নির্ণয়

Semicircles are drawn outside by taking every side of regular hexagon as a diameter. The ;perimeter of hexagon is 60 cm. Find the area of complete figure formed as such.(π\pi = 3.14) (3\sqrt3 = 1.73)

হানি নাটস

Formula: The area of a hexagon=332side2.\quad \dfrac { 3\sqrt { 3 } }{ 2 } { side }^{ 2 }.\quad

There are 6 semicircles=3 circles.

radius of each circle=r=12×\quad \dfrac { 1 }{ 2 } \times side of the hexagon.

ar.complete figure=ar.hexagon+3(ar.circle).

Here ,

perimeter of the regular hexagon=60cm.

So one side=606cm=10cm.ar.hexagon=332side2=332102cm2=3×1.73×1002cm2=259.5cm2.\quad \dfrac { 60 }{ 6 } cm=10cm.\\ \therefore \quad ar.hexagon\\ =\dfrac { 3\sqrt { 3 } }{ 2 } { side }^{ 2 }\\ =\dfrac { 3\sqrt { 3 } }{ 2 } { 10 }^{ 2 }{ cm }^{ 2 }\\ =\dfrac { 3\times 1.73\times 100 }{ 2 } { cm }^{ 2 }\\ =259.5{ cm }^{ 2 }.\quad

Again radius of each circle=r=12×\quad \dfrac { 1 }{ 2 } \times side of the hexagon= 102cm=5cm.\dfrac{10}{2}cm=5cm.

ar.(3circles)=3×π×r2=3×3.14×5×5cm2=235.5cm2.\quad ar.(3circles)=3\times \pi \times { r }^{ 2 }\\ =3\times 3.14\times 5\times 5{ cm }^{ 2 }\\ =235.5{ cm }^{ 2 }.\quad

So ar.complete figure=ar.hexagon+3(ar.circle).

=(259.5+235.5)=(259.5+235.5) cm2\quad { cm }^{ 2 }\quad

=495cm2\quad { cm }^{ 2 }

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