from Math Quest. The answer is 1:2pi
I think they want the area of the small circle to the large circle. But how would you work it out
I don't think the area of the smaller circle is less than a sixth of the area of the larger circle so the solution 1:2pi cannot be the ratio of the two circles, although I do think solving that as a separate question would be quite interesting. As CM_Tutor has posted, there is a solution that requires one to computationally calculate the angle
.
To arrive at the ratio of P to the smaller circle as 1:2pi,
Let the smaller circle be of
unit radius,
Its area is then
π.
By Pythagoras theorem, half the length of the square’s side is 1/√2 and the length of the whole side is 2/√2 or √2.
The area of the square is therefore
2.
Since each chord cuts the larger circle in the ratio 1:3, each segment is a quarter of the total area (TA) of the larger circle:
Since the segments, with individual area TA/4, overlap at P, the equation summing the areas within the large circle is:
TA = 4x Area of each segment - 4P + Area of the square
TA = 4x(TA/4) - 4P + 2
TA = TA - 4P + 2
4P = 2
P =
1/2
Therefore the ratio of the areas P: small circle = 1/2 : π = 1:2π