Example image of eyePlorer eyePlorer map for 'Triangle': Geometry Line segment Shape Collinearity Euclidean geometry Euclidean space Plane (geometry) Regular polygon Degree (angle) Internal and external angle Angle Hypotenuse Pythagorean theorem Special right triangles Dimension Polytope Simplex Euclid Euclid's Elements Supplementary angles Exterior angle theorem Triangle inequality Similarity (geometry) Theorem Congruence (geometry) Necessary and sufficient condition Trigonometric functions Trigonometry Complementary angles Law of cosines Law of sines Ceva's theorem Concurrent lines Menelaus' theorem Bisection Midpoint Circle Circumscribed circle Thales' theorem Altitude (triangle) Orthocentric system Incircle and excircles of a triangle Median (geometry) Vertex (geometry) Centroid Center of mass Nine-point circle Euler line Symmedian Euclidean vector