SOLUTION: the centers of two circles of radii 3 and 5 are 17 units apart. find the lengh of a common external tangent

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Question 1024009: the centers of two circles of radii 3 and 5 are 17 units apart. find the lengh of a common external tangent
Found 2 solutions by robertb, ikleyn:
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
The two radii must be perpendicular to the common external tangent, hence the length should be sqrt%2817%5E2+-+%285-3%29%5E2%29+=+sqrt%2817%5E2+-+2%5E2%29+=+sqrt%28285%29.

Answer by ikleyn(52794) About Me  (Show Source):
You can put this solution on YOUR website!
.
the centers of two circles of radii 3 and 5 are 17 units apart. find the length of a common external tangent.
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The two radii must be perpendicular to the common external tangent, hence the length should be sqrt%2817%5E2+-+%285-3%29%5E2%29+=+sqrt%2817%5E2+-+2%5E2%29+=+sqrt%28285%29.

See the lesson HOW TO construct a common exterior tangent line to two circles (Problem 2) in this site.