Samantha Louis

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You can classify a triangle by their angle measures using the Pythagorean Theorem.
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The Pythagorean Theorem can help classify a triangle as obtuse, acute, or right.
C² = A² + B² is the Pythagorean Theorem formula.

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C² = A² + B²
To use this formula, plug in the length of the 2 legs of the triangle into A and B and the hypotenuse into C.
If C² is greater than (>) A² + B² than the triangle is classified as obtuse.
If C² is less than (<) A² + B² than the triangle is classified acute.
If C² is equal to (=) A²+ B² than the triangle is classified as right.

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C² = A² + B²
15² = 9² + 13²
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225 = 81 + 169
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225 < 250
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The triangle is classified as acute because 225 is less than 250.
15
9
13

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C² = A² + B²
12² = 9² + 4²
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144 = 81 + 16
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144 > 97
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The triangle is classified as obtuse because 144 is greater than 97.
12
de com press or are need ed to se e th is p icture.
9
4

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C² = A² + B²
10² = 8² + 6²
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100 = 100
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The triangle is classified as right because 100 equal to 100.
6
10
8

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 http://www.education.com/reference/article/cl assifying-triangles/ http://www.cliffsnotes.com/study_guide/Exten sion-to-the-Pythagorean-
Theorem.topicArticleId-18851,articleId-
18820.html
http://www.tutorvista.com/bow/classifytriangles-learning

Definition: Two angles that are on opposite sides of the transversal outside of the lines it intersects. If the 2 two lines are parallel these angles are supplementary. This theorem stems from corresponding angle postulate.

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If consecutive angles are supplementary then the lines are parallel

Name all consecutive angle pairs

 http://www.waterfordmgmt.com/school/Prepar ed_Notes/parallel_line_geometry.pdf
 http://quizlet.com/726842/geometry-chapter-
3-vocab-thanks-to-katie-flash-cards
 http://www.cliffsnotes.com/study_guide/Testin g-for-Parallel-Lines.topicArticleId-
18851,articleId-18780.html

Summary
Lili Feinberg
This goal of this slideshow is to show you all of the possible ways to classify triangles by their sides or angles.
You can classify a triangle by its sides by calling it an isosceles triangle, a scalene triangle, or an equilateral triangle. You can classify a triangle by its angles by calling it an equiangular triangle, a right triangle, an acute triangle, or an obtuse triangle. The angle classification always goes before the side classification.

Equilateral Triangle: A triangle with all three sides equal in measure.
Isosceles Triangle: A triangle in which at least two sides have equal measure.
Scalene Triangle: A triangle where all three sides are different
Measures.
Right Triangle: A triangle that has a right angle in its interior.
Acute Triangle: A triangle with all acute angles in its interior
(less than 90 degrees).
Obtuse Triangle: A triangle with an obtuse angle in its interior
(less than 180 degrees, but more than 90 degrees).
Equiangular Triangle: A triangle having all angles of equal
Measure.

Classify the triangles by their sides and angles.
QuickT i me™ and a
dec om pres s or are needed t o s ee thi s pi c ture.
QuickTime™ and a
decompressor are needed to see this picture.
Click the space bar to reveal the answers so you can check them.
Equiangular Equilateral Right Isosceles Acute Scalene

By Katie Ostuni

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The Converse Corresponding Angle Postulate is if two lines are cut by a transversal so that corresponding angles are congruent, then two lines are parallel.

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The converse corresponding angles postulate says that if two lines are cut by a transversal so that corresponding angles are congruent then two lines are parallel.
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A converse is a situation, object or statement that is the reverse of another.
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The Converse came from the corresponding angles postulate which says if two parallel lines are cut by a transversal then corresponding angles are congruent.

Are these lines parallel ?
Answer: yes they are because of the converse corresponding angles postulate.

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Is this an example of the Converse
Corresponding Angles Postulate?
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Answer: no, this is an example of the converse alternate interior angles postulate.

 http://hotmath.com/hotmath_help/topics/ corresponding-angles-postulate.html
 http://www.regentsprep.org/regents/mat h/geometry/GPB/theorems.htm
 http://www.regentsprep.org/regents/mat h/geometry/GPB/theorems.htm