Find the circumference of the circle whose area is 4times the area of the circle with diameter 7m.
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Diameter of the circle is 7m.
∴, radius of the circle is 7/2 m.
∴, area of the circle is =22/7×(7/2)²=22/7×49/4=77/2 sq.m.
Now the first circle has the area 4 times the area of the second one.
∴, area of the first circle = 4×77/2=154 sq. m.
∴, 22/7×r²=154
or, r²=154×7/22
or, r²=49
or, r=7 (∵, radius can not be negetive)
∴, circumference of the circle = 2×22/7×7=44m
∴, radius of the circle is 7/2 m.
∴, area of the circle is =22/7×(7/2)²=22/7×49/4=77/2 sq.m.
Now the first circle has the area 4 times the area of the second one.
∴, area of the first circle = 4×77/2=154 sq. m.
∴, 22/7×r²=154
or, r²=154×7/22
or, r²=49
or, r=7 (∵, radius can not be negetive)
∴, circumference of the circle = 2×22/7×7=44m
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