18.5 Tangent Lines — The Line That Only Kisses Once
Point 4 of 5
18.5.4 A Triangle's Inscribed Circle
Core idea
Tuck the largest possible circle inside a triangle so it hugs all three sides at once — its center, where the three angle bisectors meet, is called the incenter.
Module goal. Dig deep into the borderline case of tangency, mastering a tangent's properties, its test, and the tangent-length theorem, then apply them to a triangle's inscribed circle.
eastmath.com · 18.5 Tangent Lines — The Line That Only Kisses Once · 18.5.4 A Triangle's Inscribed Circle