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AB is tangent to circle O at B. Find the length of the radius, r, for AB = 5 and AO = 13.

User DDDD
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2 Answers

3 votes

the radius is twelve

User Fady Kamal
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ΔABO is a right triangle with AB⊥BO. The radius of the circle is BO. The Pythagorean theorem applies.
AO² = AB² + BO²
13² = 5² + r²
169 -25 = r²
r = √144 = 12

The radius (r) is 12.
User SimonAx
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