Pg 316(328) - Q25
They want to know which of the following would be sufficient to determine
the radius of a circle. Well, #1 would work because you have
the length of the arc PQR. PQR is generated by a 90 degree angle,
so that would be 1/4 of the circumference. Simply multiply the value
of PQR by 4 and you have the value of the circumference, so you could certainly
calculate the radius from that. If you have the perimeter of the
triangle OPR, each of the sides, PO and PR, would be equal to the radius.
And the length PR
would be the hypotenuse of that triangle so it would be equal to
the radius times the square root of 2. So you could certainly find
the radius from that. And, we just determined that PR would simply
be the radius times the square root of two. So the answer here is
E, you could find the answer from all three.