Types of triangles

Acute and obtuse triangles

An acute triangle (or acute-angled triangle) is a triangle with three acute angles (less than 90°). An obtuse triangle (or obtuse-angled triangle) is a triangle with one obtuse angle (greater than 90°) and two acute angles. Since a triangle's angles must sum to 180° in Euclidean geometry, no Euclidean triangle can have more than one obtuse angle. Acute and obtuse triangles are the two different types of oblique triangles — triangles that are not right triangles because they do not have a 90° angle. (Wikipedia).

Acute and obtuse triangles
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What is an obtuse triangle

👉 Learn the essential definitions of triangles. A triangle is a polygon with three sides. Triangles are classified on the basis of their angles or on the basis of their side lengths. The classification of triangles on the bases of their angles are: acute, right and obtuse triangles. The cl

From playlist Types of Triangles and Their Properties

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What is an acute triangle

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From playlist Types of Triangles and Their Properties

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From playlist Types of Triangles and Their Properties

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What is an equiangular triangle

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From playlist Types of Triangles and Their Properties

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From playlist Types of Triangles and Their Properties

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From playlist Types of Triangles and Their Properties

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Animation: Types of Angles

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From playlist Angles and Right Triangles

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Determine if a triangle is acute or obtuse using the Pythagorean inequality theorem

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From playlist Types of Triangles and Their Properties

Related pages

Perpendicular | Euclidean geometry | If and only if | Perimeter | Right triangle | Angle | Arithmetic progression | Euler line | Extended side | Vertex (geometry) | Base (geometry) | Equilateral triangle | Integer triangle | Golden ratio | Isosceles triangle | Incenter | Circumcenter | Inscribed figure | Median (geometry) | Golden triangle (mathematics) | Altitude (triangle) | Heptagon | Tangent (trigonometry) | Bisection | Calabi triangle | Area | Orthocenter | Ono's inequality | Triangle | Heptagonal triangle | Centroid