Tangent Perimeter Challenge

CirclesStep 1 of 8
Circles guideYoung Math Brains home

Question

A circle touches ABAB at P,P, ACAC at Q,Q, and BCBC at R.R. If AP=10 cmAP=10\text{ cm} and BC=8 cm,BC=8\text{ cm}, find the perimeter of △ABC.\triangle ABC.
APQBRCGiven: AP = 10 cmBC = 8 cmTrace the two tangents from A

Look only at vertex AA. Which two tangent segments start from AA?

What you will learn

Use equal tangent lengths from the same external point to rebuild a triangle perimeter.

Common mistake to avoid

Do not compare tangent pieces that start from different vertices.

Make this mistake visible
Helpful?