Can someone tell me why my method is wrong.
The side of the triangle with 1/3 of the circumference of the outer circle
forms a semi-circle with a radius of 0.5.
Now we can find the area of these semi-circle's using pi*r^2 = pi*0.5^2 = 0.25pi
Since there are three of them, and they are only semi-circles, the area of all 3 would be 0.75pi/2
Now we find the area of the equilateral triangle (bh/2) = 0.5*root0.75
So therefore the total area of the circle (pi*r^2)= (0.75pi + root0.75)/2
So thereforeee..... r = root{" /pi}
= which gives me something like plusminus 0.716. (answer is 0.577 to 3dp)
If it is too hard to follow my working out don't worry about it!