SOLUTION: A,B, and C are 3 points on circle. OA is a tangent at A and OBC is a straight line. If BC=32 and OA=30 find the value of OB
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Question 1186472: A,B, and C are 3 points on circle. OA is a tangent at A and OBC is a straight line. If BC=32 and OA=30 find the value of OB Answer by greenestamps(13203) (Show Source):
The figure from the given information is of a circle and external point O, with tangent OA and secant OBC. Given the lengths of OA and BC, the length of OB is easily determined using a basic fact about tangents and secants to a circle:
(OA)^2 = (OB)(OC)
(Note, if you are interested in learning something extra from this. The formula shown comes from the fact that triangles OAB and OAC are similar.)
Let x be the length of OB and do the calculations; finding the answer will involve solving a quadratic equation.
