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Published byGodfrey Conrad Kelly Modified over 9 years ago
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Triangles Part 1
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The sum of the angles in a triangle is always equal to: 180°
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Classification By Angle Acute A triangle that has all 3 acute angles Obtuse A triangle with one obtuse angle and 2 acute angles Right A triangle with 1 right angle and 2 acute angles The two acute angles must = 90° therefore they are complimentary Equiangular A triangle with all 3 angles congruent They must each = 60 °
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Classification by Sides Scalene All three sides have different lengths Isosceles Two sides have the same length Equilateral All three sides have the same length
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Isosceles Triangles AB = CB and <A = < C Leg Base
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Equilateral Triangle An equilateral triangle is also equiangular. An equiangular triangle is also equilateral AB = BC = AC<A = <B = <C
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Classify each triangle by its angles and sides. Equilateral Scalene, Right Isosceles, Acute Isosceles, Obtuse Scalene, Acute Isosceles, Right
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Using the Distance Formula to classify triangles by their sides Find the measure of the sides of triangle DCE, then classify the triangle by sides.
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You Try Find the measure of the sides of RST. Classify the triangle by sides. RST is Scalene
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Find the missing Values Find x and the measure of each side of an equilateral triangle RST if:
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You Try Find d and the measure of each side of an equilateral triangle KLM if:
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One more! (This one is a little different) Find x and the measure of all sides if COW is isosceles, with CO=CW, and
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Finding the Measure of Missing Angles
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The sum of the angles in a triangle is always equal to: 180°
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Examples Find X:
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Exterior Angle Theorem The measure of an exterior angle of a triangle is equal to the sum of the remote interior angles. Exterior Angle: An angle formed when one side of a triangle is extended Remote Interior Angles: The interior angles of the triangle that are not adjacent to the exterior angle
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Proof of Exterior Angle Theorem
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Bigger Picture Find all missing angles
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