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Five-Minute Check (over Lesson 4–1) CCSS Then/Now New Vocabulary Theorem 4.1: Triangle Angle-Sum Theorem Proof: Triangle Angle-Sum Theorem Example 1: Real-World Example: Use the Triangle Angle-Sum Theorem Theorem 4.2: Exterior Angle Theorem Proof: Exterior Angle Theorem Example 2: Real-World Example: Use the Exterior Angle Theorem Corollaries: Triangle Angle-Sum Corollaries Example 3: Find Angle Measures in Right Triangles Lesson Menu

Classify ΔRST . A. acute B. equiangular C. obtuse D. right 5-Minute Check 1

Find y if ΔRST is an isosceles triangle with RS  RT. ___ A. 8 B. 10 C. 12 D. 14 5-Minute Check 2

Find x if ΔABC is an equilateral triangle. 5-Minute Check 3

A. ΔABC B. ΔACB C. ΔADC D. ΔCAB 5-Minute Check 4

Classify ΔMNO as scalene, isosceles, or equilateral if MN = 12, NO = 9, and MO = 15. A. scalene B. isosceles C. equilateral 5-Minute Check 5

Which is not a classification for ΔFGH? A. acute B. scalene C. isosceles D. equiangular 5-Minute Check 6

G.CO.10 Prove theorems about triangles. Mathematical Practices Content Standards G.CO.10 Prove theorems about triangles. Mathematical Practices 1 Make sense of problems and persevere in solving them. 3 Construct viable arguments and critique the reasoning of others. CCSS

You classified triangles by their side or angle measures. Apply the Triangle Angle-Sum Theorem. Apply the Exterior Angle Theorem. Then/Now

remote interior angles flow proof corollary auxiliary line exterior angle remote interior angles flow proof corollary Vocabulary

Concept 1

Concept 2

Use the Triangle Angle-Sum Theorem SOFTBALL The diagram shows the path of the softball in a drill developed by four players. Find the measure of each numbered angle. Example 1

Find the measure of 3. A. 95 B. 75 C. 57 D. 85 Example 1

Concept 3

Concept 4

GARDENING Find the measure of FLW in the fenced flower garden shown. Use the Exterior Angle Theorem GARDENING Find the measure of FLW in the fenced flower garden shown. Answer: So, mFLW = 2(80) – 48 or 112. Example 2

The piece of quilt fabric is in the shape of a right triangle The piece of quilt fabric is in the shape of a right triangle. Find the measure of ACD. A. 30 B. 40 C. 50 D. 130 Example 2

Concept 5

Find the measure of each numbered angle. Find Angle Measures in Right Triangles Find the measure of each numbered angle. Example 3

Find m3. A. 50 B. 45 C. 85 D. 130 Example 3

HOMEWORK Pgs. 250-252 #’s1-15, 17-22,24-29, 30-32, 36,37,49

End of the Lesson