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4.2 Angles of Triangles. What you’ll learn: To apply the Angle Sum Theorem To apply the Exterior Angle Theorem. Theorems. Theorem 4.1 Angle Sum Thm The sum of the measures of the angles of a triangle is 180. Theorem 4.2 Third Angle Thm
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4.2 Angles of Triangles What you’ll learn: To apply the Angle Sum Theorem To apply the Exterior Angle Theorem
Theorems Theorem 4.1 Angle Sum Thm The sum of the measures of the angles of a triangle is 180. Theorem 4.2 Third Angle Thm If 2 angles of one triangle are congruent to 2 angles of a second triangle, then the third angles of the triangles are congruent. Theorem 4.3 Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the measures of the 2 remote interior angles. Remote Interior angles Ext. angle
Corollaries Corollary – a statement that can easily be proven with a related theorem (a corollary to that theorem) These can be used in proofs. Corollary 4.1 The acute angles of a right triangle are complementary. Corollary 4.2 There can be at most one right or obtuse angle in a triangle
Find the missing angle measures 1 1. 1=63 2=63 3=38 2. 1=70, 2=110, 3=46 4=102, 5=37 3. 1=20, 2=140, 3=40 20 2 3 43 79 1 2 74 3 38 32 1 4 3 5 2 29 41 64
