May 15, 2015

Lessons, videos, exercises, and text from CK-12.

Additional resources available at this site.

- Mathematics > General
- Mathematics > Geometry

- Grade 9
- Grade 10

Make sense of problems and persevere in solving them.

Reason abstractly and quantitatively.

Use appropriate tools strategically.

Attend to precision.

Look for and make use of structure.

(+) Derive the formula A = 1/2 ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side.