Question

Construct a common internal tangent for circle A and circle B.

Here's the link: https://heritagehomeschoolks.ignitiaschools.com/media/g_geo_2014/3/1003l14b.html (it's question 3)

Please explain how you figured this out. Thank you!

Answer 1

see
http://www.mathopenref.com/consttangents.html

scroll down to near the bottom to find other constructions related to circles and tangents.

Answer 2

Thanks @phi