Drill 1) 39 + 28 + x = 180, solve for x 2) How many degrees do the interior angles of a triangle add up to. 3) What type of triangle has an angle that.

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Triangles TOPIC 9 LESSON 9-5.

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Presentation transcript:

Drill 1) 39 + 28 + x = 180, solve for x 2) How many degrees do the interior angles of a triangle add up to. 3) What type of triangle has an angle that is 100 degrees and has all three sides of different lengths.

2.1 Triangles

Triangle Angle Sum Theorem The sum of the interior angles of a triangle add up to 180 degrees.

Types of Triangles Equilateral: All three sides equal Isosceles: At least two sides equal Scalene: No sides are the same Equiangular: All angles are equal Acute: All angles are less than 90 degrees Right: One angles is a right angle (90 degrees) Obtuse: One angle is greater than 90 degrees

Types of Angles Exterior Angles “w” is the exterior angle because it is adjacent to one of the interior angles. Remote Interior Angle “x” and “y” are remote interior angles in reference to “w” because they are the two interior angles not connected to angle “w”.

X Y Z W X + Y 50 60 70 110 110 75 40 65 115 115 30 55 95 85 85 75 45 60 120 120

Exterior Angle Theorem Exterior Angle = Sum of two remote interior Angles

120o yo 50o xo

(x+17)° (x+3)° (3x+10)° 45° 57° y° z° 10° 22° a° 40° c° b° a° e° b° 60° 78° c° d° 50° 15° y° z° 60° x°