9.2. Tangent Lines http://www.ck12.org
Solution:BecauseCBis tangent,AB⊥CB, making 4 ABCa right triangle. We can use the Pythagorean Theorem to
findAC.
52 + 82 =AC^2
25 + 64 =AC^2
89 =AC^2
AC=
√
89
Example B
FindDC, in
⊙
A. Round your answer to the nearest hundredth.Solution:
DC=AC−AD
DC=
√
89 − 5 ≈ 4. 43
Example C
Find the perimeter of 4 ABC.
Solution:AE=AD,EB=BF, andCF=CD. Therefore, the perimeter of 4 ABC= 6 + 6 + 4 + 4 + 7 + 7 =34.
We say that
⊙
Gisinscribedin 4 ABC. A circle is inscribed in a polygon, if every side of the polygon is tangent to
the circle.