Question

What’s the diameter of a circle if the area is 31,416

Answer 1

The diameter of the circle is 10.

Answer 2

Answer: The diameter of the circle is: "200" .

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Note:

We are asked to find the "diameter, d" of a circle;
{with area, "A" , equal to: "31,416" } .
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Area of a circle, "A" :
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A = π r² ;

in which: "r" = radius ;

Let us use: "3.1416" for "π"
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The diameter, "d" :
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d = 2r ;
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We need to find "r" ; so we can find "d" ;
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Given: A = 31,416 ;

A = π r² ;

31,416 = (3.1416) * (r²) ;

↔ (3.1416) * (r²) = 31,416 ;

Divide each side of the equation by: "(3.1416)" ;

[(3.1416) * (r²) ] / (3.1416) = (31,416) / (3.1416) ;

to get:

r² = 10,000

Now, take the "positive" square root of EACH SIDE of the equation; to isolate "r" on one side of the equation; & to solve for "r" ;

√(r²) = √(10,000) ;

r = 100 ;
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We are asked to find the diameter, "d" ; of the circle:

d = 2 r ;

d = 2 (100) ;

d = 200 .
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The answer is: " 200 " .
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The diameter of the circle is: " 200 " .
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