Angle relationships and unknown angle problems
This lesson first explains supplementary and vertical angles. Then we look at a variety of "angle puzzles", or problems with an unknown angle, and solve those using these basic principles. I also write an equation for each problem, to help students learn to both write and solve equations, since this lesson belongs to my pre-algebra course.
See also
Angles in a triangle — video lesson
Math Mammoth Geometry 3 — a self-teaching worktext with explanations & exercises (grades 4-5)
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