Unit 3, Lesson 18
Using Equations to Solve for Unknown Angles
Accelerated 7
18.1
Warm-up
Tyler thinks that this figure has enough information to figure out the values of and .
Do you agree? Explain your reasoning.
18.2
Activity
Elena and Diego each wrote equations to represent these diagrams. For each diagram, decide which equation you agree with, and then solve it.
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Elena:
Diego:
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Elena:
Diego:
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Elena:
Diego:
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Elena:
Diego:
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Elena:
Diego:
18.3
Activity
Find the unknown angle measures. Show your thinking. Organize it so it can be followed by others.
Student Lesson Summary
To find an unknown angle measure, sometimes it is helpful to write and solve an equation that represents the situation. For example, suppose we want to know the value of in this diagram.
Using what we know about vertical angles, we can write the equation to represent this situation. Then we can solve the equation.
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