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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

Triangles - Classification By Angles

If $\angle A = 45 ^\circ, \angle B = 35 ^\circ$ and $\angle C = 100 ^\circ$ in the above triangle, what type of triangle is $\triangle ABC?$

right triangle obtuse triangle regular triangle acute triangle

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by Brilliant Staff

If $ABCDEFGH$ is a cube with side length $5,$ what is $\angle DEG ?$

\displaystyle{{60}^\circ}

\displaystyle{{90}^\circ}

\displaystyle{{45}^\circ}

\displaystyle{{30}^\circ}

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by Brilliant Staff

The length of $\overline {AB}$ is the same as that of $\overline {AC}$ in the above triangle. If $\angle B =74^\circ,$ what is $\angle C ?$

\displaystyle {{74}^\circ }

\displaystyle {{78}^\circ }

\displaystyle {{76}^\circ }

\displaystyle {{72}^\circ }

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by Brilliant Staff

Suppose that $\angle A = 80 ^\circ, \angle B = 55 ^\circ$ and $\angle C = 45 ^\circ .$ If points $D, E$ and $F$ are the midpoints of $\overline{BC}, \overline{CA}$ and $\overline{AB},$ respectively, what type of triangle is $\triangle DEF ?$

Note: The above diagram is not drawn to scale.

regular triangle right triangle obtuse triangle acute triangle

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by Brilliant Staff

What do we call a triangle which has exactly 2 equal angles?

isosceles triangle right triangle equilateral triangle acute triangle

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by Brilliant Staff