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The SAT Question Everyone Got Wrong
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this post was submitted on 01 Dec 2023
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So I'm confused. I saw this and initially thought it was just a matter of circumference. Suppose the radius of circle A is 10 and the radius of circle B is twice that amount, so it's 20
The formula to find the circumference of a circle is C = 2πr
So for circle A;
2π10 = 62.831
And for circle B;
2π20 = 125.663
Then to find the difference in circumferences, divide them
125.663/62.831 = 2.000
Therefore, it should take two rotations to rotate one circle around the other
What am I getting wrong here?
There's one extra-rotation from an external perspective due to the revolution of one around the other. So the formula is r1 / r2 + 1.
This extra-rotation doesn't appear from the point of view of the circles, or if you consider the circles as two stationary gears