Question

1. AB is tangent to circle O at B. The diagram is not drawn to scale.
If AB = 9 and AO = 21.6, what is the radius(r)? Round the answer to the nearest tenth.

Answer 1

using the pythagorean theorem, we can say

OB^2 + AB^2 = OA^2

r^2 + 9^2 = 21.6^2

r = ???

Answer 2

21.6 - 9 = 12.6
Is that correct?

Answer 3

not quite

Answer 4

r^2 + 9^2 = 21.6^2

r^2 + 81 = 466.56

r^2 = 466.56 - 81

r^2 = 385.56

r = ???

Answer 5

r = 19.6

Answer 6

19.6356818 which rounds to 19.6, correct