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Missing Angles Notes

Last year, I started my pre-calculus class off with geometry review. The first topic we tackled was finding missing angles in triangles. This set of notes was the perfect opportunity to pull out some of my favorite school supplies: colored pens and highlighters!

baskets of colored ink pens and highlighters

The purpose of these notes was to review three key geometry concepts regarding angles:

  1. The sum of the interior angles in a triangle is always 180 degrees.
  2. Angles on one side of a straight line always sum to 180 degrees.
  3. Vertical angles are always congruent.
missing angles geometry notes

My school uses an Algebra 1, Geometry, Algebra 2, Pre-Calculus sequence, so by the time I get students in Pre-Calculus it has been quite a while since they have done any geometry.

missing angles geometry notes

In addition to preparing my students to possibly take calculus in the future, my other main goal for the course is to help them refresh their understanding of previously learned math content so they can hopefully maximize their ACT scores for scholarship opportunities and the college admissions process.

missing angles geometry notes

These missing angle questions pop up frequently on past ACT exams, so it makes sense to include this in our geometry review before we move on to right triangle trigonometry and SOH CAH TOA.

missing angles geometry notes

Free Download of Missing Angles Notes

These missing angle notes that I put together are available to download as both a WORD file and a PDF.


Missing Angle Notes (PDF) (66 downloads)


Missing Angle Notes (WORD) (29 downloads)