Warm-up Classify each angle: 1. 2. 3. 4. Solve for x. 1. 2. 3. 4. Solve for x. (6x + 2) + (3x + 5) + (x + 3) = 180

Triangles and Angles Unit 4 Triangle Properties Section 4.1 Slides 1 - 12 Section 4.1

Triangles can be classified in two ways: Angle measures Right Acute Obtuse Side lengths Scalene Equilateral Isosceles

Classifying a triangle by its angle measurement Right Triangle: A right triangle has one right angle

Classifying a triangle by its angle measurement Acute Triangle: An acute triangle has three acute angles (less than 90°)

Classifying a triangle by its angle measurement Obtuse Triangle: An obtuse triangle has one obtuse angle (more than 90°)

Classifying a triangle by its side lengths Scalene Triangle: A scalene triangle has no congruent sides (all different side lengths)

Classifying a triangle by its side lengths Equilateral Triangle: An equilateral triangle has three congruent sides (all side lengths are the same)

Classifying a triangle by its side lengths Isosceles Triangle: An isosceles triangle has at least two congruent sides http://www.youtube.com/watch?v=DUNxLGhFCqM&safety_mode=true&persist_safety_mode=1&safe=active

Triangle Sum Investigation:

Triangle Sum Conjecture Slides 18 - 21 Triangle Sum Conjecture The sum of the measures of the angles in EVERY triangle is __________ degrees. C; m<X + m<Y + m<Z = 180 R: Triangle sum theorem

Ex 1 Find x and classify the triangle. 53 42 x x = 85

Example 2: Solve for x and classify the triangle. 52 (7x + 5) (5x + 3)

Example 3: Solve for x and classify the triangle. (3x – 5) (46 – x)

Example 4: Find the measures of the missing angles. 5 2 60 135 1 3 4

Example 5: Use the diagram to find mMJK.