Question

AB is Tangent to circle O at B. if AB = 7 and AO = 17.4, what is the length of radius r to the nearest tenth?

Answer 1

The answer to the question is 15.92

Answer 2

The angle the radius makes with AB is a right angle, so the Pythagorean theorem applies.
  r² = 17.4² - 7² = 253.76
  r = √253.76 ≈ 15.9

The length of radius r is about 15.9.