CIRCLES

Question

If the radius of a cirlce is triples what is the ratio of half the original circle area to area of the entire new circle

devashish · Answer

What is 'triples' ??

Jinglander · Answer

Triple

Posted from my mobile device

amitjash · Answer

1/36

Let the radious be 2R, half of radious is R and Tripple of the radiuls is 6R

Area of smaller circle = PI R^2

Are of bigger circle = PI (6R)^2 = PI * 36 R^2

Ratio = 1/36

michael1324 · Answer

First post after lurking here a bit ^^
Givens: The old circle has radius R, and the new circle has radius 3R.
Looking for: (1/2*Area(Old circle))/(Area(New circle)) ->
(1/2)*pi*R^2/(pi(3R)^2) ->
(1/2)*pi*R^2/(9*pi*R^2)->
(1/2)/(9)->
1/18

efet · Answer

say r = 1
tripled circle will have pi*(3*1)^2 = 9pi
original circle pi*1^2 = pi

pi/2/9pi

1/18

whiplash2411 · Answer

Fairly simple question. Area of a circle with respect to it's radius is  /pi*r^2  if radius is r. So now we have tripled the radius and we are taking half the original area.

New Circle Area  = \pi*(3r)^2 = 9\pi*r^2 
Half of Old Circle Area  = \frac{\pi*r^2}{2}

Ratio:  = \frac{\frac{\pi*r^2}{2}}{9\pi*r^2} = \frac{1}{18}

dungtd · Answer

"Triple of radius is 3r, NOT 6R." Thus, the answer is 1/18.

rlevochkin · Answer

My reasoning

pi*r^2 is the frmula for the circle square. Let x be a factror.

so, x = pi*(3r^2)/pi(.5r)^2,

get rid of pi,

9r^2/.25r^2= 36

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