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Example 2-3b Objective Find missing angle measures in triangles and classify triangles by their angles and sides

Example 2-3b Vocabulary Triangle A figure formed by three line segments that intersect only at their endpoints

Example 2-3b Vocabulary Acute triangle A triangle having three acute angles

Example 2-3b Vocabulary Obtuse triangle A triangle having one obtuse angle

Example 2-3b Vocabulary Right triangle A triangle having one right angle

Example 2-3b Vocabulary Scalene triangle A triangle with no congruent sides

Example 2-3b Vocabulary Isosceles triangle A triangle that has at least two congruent sides

Example 2-3b Vocabulary Equilateral triangle A triangle that has three congruent sides

Lesson 2 Contents Example 1Find a Missing Angle Measure Example 2Classify Triangles Example 3Classify Triangles

Example 2-1a Find the value of x in The sum of the 3 angles of a triangle = /3 Write an equation Replace m  P with Replace m  Q with Define variable as m  r m  R Bring down = m  R = 180

Example 2-1a Find the value of x in Combine “like” terms 1/ m  R = Ask “what is being done to the variable”? The variable is being added by 63 Do the inverse on both sides of the equal sign Bring down + m  R = m  R = 180

Example 2-1a Find the value of x in Bring down 63 1/ m  R = m  R = Subtract Bring down + m  R = m  R = 180 Subtract m  R = Combine “like” terms 0 Bring down + m  R = 0 + m  R = Combine “like” terms 0 + m  R = 117

Example 2-1a Find the value of x in Use the Identity Property to add 0 + m  R 1/ m  R = m  R = m  R = m  R = m  R =0 + m  R = 117 m  R = 117 Add dimensional analysis m  R = Answer:

Example 2-1b Answer: m  I = 35 0 Find the value of x in 1/3

Example 2-2a Classify the triangle by its angles and its sides. Answer: right, isosceles triangle 2/3  B is a right angle Angles Right triangle Sides Segments AB and BC are congruent Isosceles triangle

Example 2-2b Classify the triangle by its angles and its sides. Answer: acute, equilateral triangle 2/3

Example 2-3a Classify the triangle by its angles and its sides. Answer: Obtuse, scalene triangle 3/3  Q is an obtuse angle Angles Obtuse triangle No sides are congruent Sides Scalene triangle

Example 2-3b Classify the triangle by its angles and its sides. Answer: right, scalene triangle * 3/3

End of Lesson 2 Assignment Lesson 6:2Triangles and Angles All