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Encyclopedia>Geometry>Planar Figures>Triangles

Triangles

Concepts Quadrilaterals Triangles

Triangle Attributes The Pythagorean Theorem Concurrent Lines and Collinear Points

Similar Figures The Golden Ratio

Geometric Constructions

Perspective Drawing

What Is a Triangle?
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What Is the Sum of Angles of a Triangle?
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What Is the Formula for the Perimeter of a Triangle?
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What Is the Formula for the Area of a Triangle?
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What Are 30°–60°–90° Triangles?
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What Does the Pythagorean Theorem State?
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What Can the Pythagorean Theorem be Used For?
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What Is the Pythagorean Theorem Formula?
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What Are the Four Centers of a Triangle?
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How to Find the Circumcenter of a Triangle
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How to Find the Incenter of a Triangle
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How to Find the Centroid and Medians of a Triangle
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How to Find the Orthocenter and Altitudes of a Triangle
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What Is the Euler Line?
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