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-WARM UP 4.2 -Khan Academy. -QUIZ 3.3 - 3.4. ESSENTIAL QUESTION How you calculate a ngle measures in Triangles?. Triangle Sum Theorem Theorem 4.2. The sum of the measures of the angles of a triangle is 180. Example 1. Find an Angle Measure.
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-WARM UP 4.2-Khan Academy -QUIZ 3.3 - 3.4
ESSENTIAL QUESTION • How you calculate angle measures in Triangles?
Triangle Sum TheoremTheorem 4.2 • The sum of the measures of the angles of a triangle is 180
Example 1 Find an Angle Measure GivenmA = 43°andmB = 85°, findmC. SOLUTION C has a measure of 52°. ANSWER Check your solution by substituting 52° for mC. 43° + 85° + 52° = 180°
Example 2 Find Angle Measures ∆ABCand ∆ABDare right triangles. SupposemABD =35°. a. b. FindmBCD. FindmDAB. SOLUTION a. mDAB + mABD= 90° mDAB + 35°– 35° = 90° – 35° mDAB= 55° mDAB + mBCD= 90° b. 55°+ mBCD = 90° mBCD= 35°
Checkpoint Find an Angle Measure FindmA. FindmB. FindmC. 1. 2. 3. ANSWER 65° ANSWER 75° ANSWER 50°
Exterior Angle Theorem Theorem 4.2 The measure of an exterior angle of a triangle is equal to the sum of the measures of the two nonadjacent interior angles.
Example Find an Angle Measure GivenmA = 58°andmC = 72°, findm1. SOLUTION m1= mA + mC = 58° + 72° = 130° 1 has a measure of 130°. ANSWER
Checkpoint Find an Angle Measure Findm2. Findm3. 4. 5. ANSWER 120° ANSWER 155°
Classify the triangle by its angles and by its sides. 1. obtuse, isosceles ANSWER REVIEW acute, isosceles ANSWER 2.
3. Identify which side is opposite each angle. BC is oppositeA; AB is opposite C; AC is oppositeB ANSWER equilateral or equiangular ANSWER 4. Brittani built a garden bed frame by nailing together three equal lengths of wood to form a triangle. What type of triangle did she create?