Triangle Inequality Theorem
10th GradeMath45 min
Learning Objective
I can determine if three side lengths form a triangle using the triangle inequality theorem.
Lesson Flow
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Guided Notes
Key concepts students will learn:
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The triangle inequality theorem states that the sum of the two smaller sides of a triangle must be greater than the longest side.
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To find the possible range for the third side of a triangle, you must subtract the two given sides to find the lower bound and add them to find the upper bound.
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If given two sides of a triangle of lengths 7 and 5, the third side (x) must fall in the range 2 < x < 12.
Practice
9 questions • Multiple choice & Short answer
Exit Ticket
“The lengths of two sides of a triangle are 8 cm and 10 cm. What is a possible length for the third side? Explain your answer.”
Teacher Guide
Get the complete package:
- Answer keys for all questions
- Differentiation strategies
- Extension activities
- Printable student handouts
