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Because the area of a circle is pi*radius2.

So, if you triple the radius to 3*radius, the area becomes

pi*(3*radius)2 = pi*(32*radius2) = pi*9*radius2 that is, 9 times the original area.

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10y ago
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1y ago

The area of a circle is given by the formula A = πr^2, where r is the radius. If you triple the radius (r), the new radius becomes 3r. Substituting this into the formula, you get A = π(3r)^2 = 9πr^2. The area is multiplied by 9 because the radius is squared in the formula.

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Q: Why the area is multiplied by 9 if you triple a radius?
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Related questions

What happens to the area of a circle if you triple a radius?

When you triple the radius of the circle . . . -- The diameter also triples. -- The circumference also triples. -- The area is multiplied by 9 .


What happen to the area of circle when the radius is tripled?

If you triple the radius of a circle, the area will increase by 9. Area is proportional to the square of the radius.


What happens to the area of a circle when the radius is triple?

The area increases as the square of the radius (or diameter). So if you double the radius you * 4 (quadruple) the area. Treble the radius, you *9 the area.


If you triple the radius of a circle what happens to the area?

The result is 9 time the original.


What happens to the area of a circle when you triple the radius?

As the area of a circle is pi*radius2 the increase in area is a factor of 32. So tripling the radius gives an increase in area by a factor of 9.


How do you find the radius squared?

Radius squared is half of the diameter multiplied by itself. Example: diameter is 6 inches, radius is 3 inches (half of diameter), radius squared is 9 inches (radius multiplied by itself 3 x 3 = 9).


What is the area of a 12 inch and a 9 inch circle?

If you are talking about 9 and 12 inch diameter, then divide both by 2 to get the radius. The area of a circle is pi (3.1415 is good for most calculations) multiplied by the square of the radius. So for the 12 inch circle, the radius is 6. The square of the radius is 36, and multiplying this by pi gives approximately 113.1 square inches. Now the 9 inch circle has a radius of 9/2 or 4.5. Squaring this we get 20.25, which multiplied by pi is approximately 63.6 square inches. If 9 and 12 were already the radius in the problem, just don't divide by 2 since you already have the radius.


How would the area of a circumerancebe affected when the diameter of a circle is doubled or triple?

First of all, there's no such thing as the "area of a circumference". The distancearound the circle is called the "circumference", and the area of the circle is calledthe "area of the circle".-- When the diameter of the circle is doubled, the circumference is doubledand the area is multiplied by 4.-- When the diameter of the circle is tripled, the circumference is tripledand the area is multiplied by 9.-- When the diameter of the circle is multiplied by N, the circumference ismultiplied by N and the area is multiplied by N2 .


What is the area of a circle with a radius of 9 ft?

A circle with a radius of 9 feet has an area of 254.47 square feet.


What happens to the area of a circle when the radius is doubled tripled?

The area increases as the square of the radius (or diameter). So if you double the radius you * 4 (quadruple) the area. Treble the radius, you *9 the area.


What is the area of a circle if the radius is 9?

i believe that it is 18 if the radius is 9 edit: wrong, area = pi*radius^2 so it's 3.1415926535*81=254.469


When you triple the dimensions of a figure how does this affect the area of the figure?

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