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Class Greeting. Objective: The students will apply Inequalities in One Triangle. Exterior Angle Inequality Theorem. If an is an exterior of a ∆, then its measure is greater than the measure of either of its remote interior s. m 1 > m 3 m 1 > m 4. m 5 > m 3 m 5 > m 2.
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Objective: The students will apply Inequalities in One Triangle.
Exterior Angle Inequality Theorem • If an is an exterior of a ∆, then its measure is greater than the measure of either of its remote interior s. m1 > m 3m 1 > m 4 m5 > m 3m 5 > m 2
Example 1 Use the Exterior Angle Inequality Theorem to list all of the angles whose measures are less than m14. By the Exterior Angle Inequality Theorem, m14 > m2, m14 > m4, m14 > m11, and m14 > m4+m3, therefore m14 > m3. Answer:The angles that are greater than m14 are 2, 4, 11 and 3.
Example 2: Use the Exterior Angle Inequality Theorem to list all angles whose measures are greater than m5. By the Exterior Angle Inequality Theorem, m10 > m5, m12 > m5, andm17 > m5. Answer: The angles that are greater than m5 are 10,12 and17.
Use the Exterior Angle Inequality Theorem to list all of the angles that satisfy the stated condition. a. all angles whose measures are less than m4 b. all angles whose measures are greater than m8 Your Turn: Answer:5, 2, 8, 7 Answer:4, 9, 5
The positions of the longest and shortest sides of a triangle are related to the positions of the largest and smallest angles.
The shortest side is , so the smallest angle is F. The longest side is , so the largest angle is G. Example 2A: Ordering Triangle Side Lengths and Angle Measures Write the angles in order from smallest to largest. The angles from smallest to largest are F, H and G.
The smallest angle is R, so the shortest side is . The largest angle is Q, so the longest side is . The sides from shortest to longest are Example 2B: Ordering Triangle Side Lengths and Angle Measures Write the sides in order from shortest to longest. mR = 180° – (60° + 72°) = 48°
The shortest side is , so the smallest angle is B. The longest side is , so the largest angle is C. Check It Out! Example 2a Write the angles in order from smallest to largest. The angles from smallest to largest are B, A, and C.
The smallest angle is D, so the shortest side is . The largest angle is F, so the longest side is . The sides from shortest to longest are Check It Out! Example 2b Write the sides in order from shortest to longest. mE = 180° – (90° + 22°) = 68°
Lesson Summary: Objective: The students will apply Inequalities in One Triangle.
Preview of the Next Lesson: Objective: The students will review for Lesson 5-1 to 5-3 test.