CK-12 Geometry - Second Edition

(Marvins-Underground-K-12) #1

1.6. Classifying Polygons http://www.ck12.org


Isosceles Triangle:Whenat leasttwo sides of a triangle are congruent.


Equilateral Triangle:When all the sides of a triangle are congruent.


Note that by the definitions, an equilateral triangle is also an isosceles triangle.


Example 4:Classify the triangle by its sides and angles.


Solution:We are told there are two congruent sides, so it is an isosceles triangle. By its angles, they all look acute,
so it is an acute triangle. Typically, we say this is an acute isosceles triangle.


Example 5:Classify the triangle by its sides and angles.


Solution:This triangle has a right angle and no sides are marked congruent. So, it is a right scalene triangle.

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