Unit 3, Lesson 18
Using Equations to Solve for Unknown Angles
Accelerated 7
Preparation
Lesson Narrative
In this lesson, students practice writing and solving equations of the form in the context of finding unknown angle measures. Students examine the structure of angle relationships as they compare a diagram to possible equations that could be used to represent the angle relationships (MP7).
The angles used in this lesson connect to earlier work with supplementary, complementary, and vertical angles, giving additional opportunities to build fluency with these concepts.
Use this optional lesson any time after Lesson 10 of this unit.
This lesson includes a set of practice problems, even though the last lesson in a unit typically does not. The problems are included here to give students more practice writing and solving equations to find unknown angles. If time is limited, consider focusing on practice problems 1–3.
- Determine whether a given equation represents the relationship between angles shown in a diagram.
- Solve an equation that represents a relationship between angle measures, and explain (in writing and using other representations) the reasoning.
- Write an equation of the form $px+q=r$ or $p(x+q)=r$ to represent the relationship between angles in a given diagram.
Let’s figure out missing angles using equations.
Required Preparation
None