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Geometry

Classification of Triangles

Concept Quizzes

Classification of Triangles Warmup
Triangles - Classification By Angles
Triangles - Classification by Sides
Properties of Equilateral Triangles
Properties of Isosceles Triangles

Challenge Quizzes

Classification of Triangles: Level 1 Challenges
Classification of Triangles: Level 2 Challenges
Classification of Triangles: Level 3 Challenges

Properties of Isosceles Triangles

$\triangle ABC$ is an isosceles triangle such that the lengths of $\overline{AB}$ and $\overline{AC}$ are equal. If $\angle BAC=78 ^\circ ,$ what is $\angle ABC$ in degrees?

56 46 78 51

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by Brilliant Staff

In the above diagram, $\triangle ACD$ is an isosceles triangle with the length of $\overline{CA}$ equal to the length of $\overline{CD}.$ If $\overline{CD}$ bisects $\angle ACB$ and $\angle ABC =a= 66^{\circ},$ what is three times $\angle ACD$ in degrees?

52 46 50 48

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by Brilliant Staff

In the above diagram, $\angle DCE=a=99^\circ, \lvert \overline{AB}\rvert =\lvert \overline{AC}\rvert=\lvert \overline{CE}\rvert,$ and $\overline{BE}$ and $\overline{BD}$ are both straight lines. What is the value of $\angle ABC(=x)$ in degrees?