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Lesson Menu Five-Minute Check (over Lesson 4–1) 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
Over Lesson 4–1 A.A B.B C.C D.D 5-Minute Check 1 A.acute B.equiangular C.obtuse D.right Classify ΔRST.
Over Lesson 4–1 A.A B.B C.C D.D 5-Minute Check 2 A.8 B.10 C.12 D.14 Find y if ΔRST is an isosceles triangle with RS RT. ___
Over Lesson 4–1 A.A B.B C.C D.D 5-Minute Check 3 A.2 B.4 C.6 D.8 Find x if ΔABC is an equilateral triangle.
Over Lesson 4–1 A.A B.B C.C D.D 5-Minute Check 4 A.ΔABC B.ΔACB C.ΔADC D.ΔCAB
Over Lesson 4–1 1.A 2.B 3.C 5-Minute Check 5 A.scalene B.isosceles C.equilateral Classify ΔMNO as scalene, isosceles, or equilateral if MN = 12, NO = 9, and MO = 15.
Over Lesson 4–1 1.A 2.B 3.C 4.D 5-Minute Check 6 A.acute B.scalene C.isosceles D.equiangular Which is not a classification for ΔFGH?
Then/Now You classified triangles by their side or angle measures. (Lesson 4–1) Apply the Triangle Angle-Sum Theorem. Apply the Exterior Angle Theorem.
Vocabulary auxiliary line exterior angle remote interior angles
Concept 1
Concept 2
Example 1 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.
A.A B.B C.C D.D Example 1 A.95 B.75 C.57 D.85 Find the measure of 3.
Concept 3
Concept 4
Example 2 Use the Exterior Angle Theorem GARDENING Find the measure of FLW in the fenced flower garden shown.
A.A B.B C.C D.D Example 2 A.30 B.40 C.50 D.130 The piece of quilt fabric is in the shape of a right triangle. Find the measure of ACD.
Concept 5
Example 3 Find Angle Measures in Right Triangles Find the measure of each numbered angle. m 1 = 104, m 2 = 76, m 3 = 42, m 4 = 48, m 5 = 49
A.A B.B C.C D.D Example 3 A.50 B.45 C.85 D.130 Find m 3.
End of the Lesson