http://www.ck12.org Chapter 9. Circles
52 + 552 =AC^2
25 + 3025 =AC^2
3050 =AC^2
AC=
√
3050 = 5
√
122
- BecauseAEis tangent to both circles, it is perpendicular to both radii and 4 ABCand 4 DBEare similar. To find
DB, use the Pythagorean Theorem.
102 + 242 =DB^2
100 + 576 = 676
DB=
√
676 = 26
To findBC, use similar triangles.
5
10
=
BC
26
−→BC= 13
DC=AB+BC= 26 + 13 = 39
Interactive Practice
MEDIA
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Determine whether the given segment is tangent to
⊙
K.