13
good luck
radius
radius
x2 + y2 = 25
x2 + y2 = 25
x2 + y2 =144
17
15 APEX =)
radius
radius
The circle of radius five centered at the origin.
x2 + y2 = r2 describes a circle, radius r, centred on the origin. r is thus sqrt(25 + 144) ie 13 units.
If that equals 16 then the radius is 4
x2 + y2 = 25
x2 + y2= 16
x2 + y2 = 25
x2 + y2 = 36
x2 + y2 = 49