4. Given r = 3, arc length PR = pi.
We are asked to find the angle made by the arc POR ?
circumference = 2*pi*3 = 6pi.
We know total angle made by the circle is 360 deg.
6pi = 360 deg.
pi = 360/6 = 60 deg.
5. Given PR is diameter. arc length PQ = 4*pi. OQ is perpendicular to PR.
Find QR length.
The minor arc PQ is a quadrant since PR is the diameter and OQ is perpendicular to PR.
so 4pi is 1/4th of the total circumference. arc length QR is also equal to 4*pi.
(1/4) * 2*pi*r = 4 * pi.
r = 8.
OQ = OR = 8.
QR = sqrt(8^2 + 8^2) = sqrt(128) = 11.31