Congruent Triangles: SAS, SSS, ASA

Congruent Triangles: SAS, SSS, ASA
Demonstrates with animation the various relationships of angles and sides to congruency in triangles.


See animation at:
www.gogeometry.com/geometry/congruent_triangle_journey_1977.htm

Triangle Centers Journey (1976).

Journey to the Center of a Triangle
Incenter, Circumcenter, Centroid, Orthocenter.


See animation at:
http://www.gogeometry.com/center/triangle_centers_journey.htm

Twin Prime Conjecture, Euclid 300 B.C.

Twin Prime Conjecture
is a famous unsolved problem in number theory discovered by Euclid.


See animation at:
www.gogeometry.com/geometry/twin_prime_number_conjecture_euclid.htm

Elearn Geometry Problem 198: Triangle, Quadrilateral, Angle

See complete Problem 198 at:
www.gogeometry.com/problem/p198_triangle_quadrilateral_circle_angle.htm

Triangle, Quadrilateral, Circle, Angles. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 197: Triangle area

See complete Problem 197 at:
www.gogeometry.com/problem/p197_triangle_area_side_inradius_exradius.htm

Area of a Triangle, Side, Inradius, and Exradius. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 196: Inradius and Exradii Formula

See complete Problem 196 at:
www.gogeometry.com/problem/p196_triangle_inradius_exradius_formula.htm

Triangle: inradius and exradii formula. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 195

See complete Problem 195 at:
www.gogeometry.com/problem/p195_area_of_a_triangle_inradius_exradius.htm

Area of a Triangle, Inradius, Exradii. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 194

See complete Problem 194 at:
www.gogeometry.com/problem/p194_area_of_a_triangle_semiperimeter_exradius.htm

Area of a Triangle, Semiperimeter, Exradius. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 193

See complete Problem 193 at:
www.gogeometry.com/problem/p193_area_of_a_triangle_semiperimeter_inradius.htm

Area of a Triangle, Semiperimeter, Inradius. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 192

See complete Problem 192 at:
www.gogeometry.com/problem/p192_circle_diameter_chord_area.htm

Circle, Diameter, Chord, Perpendicular, Triangle, Area. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 191

See complete Problem 191 at:
www.gogeometry.com/problem/p191_triangle_altitude_square_area.htm

Triangle, Altitudes, Orthocenter, Squares, Areas. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 190, Circle

See complete Problem 190 at:
www.gogeometry.com/problem/p190_tangent_circle_diameter_perpendicular.htm

Tangent circles, Tangent chord, Perpendicular, Distance. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 189

See complete Problem 189 at:
www.gogeometry.com/problem/p189_square_fact.htm

Squares, Distances. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 188

See complete Problem 188 at:
www.gogeometry.com/problem/p188_square_45_degrees_problem.htm

Square, Diagonal, 45 Degrees Angle. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

DARPA Mathematical Challenges 2009

Interactive Mind Map
DARPA is soliciting innovative research proposals in the area of DARPA Mathematical Challenges, with the goal of dramatically revolutionizing mathematics.



See a complete interactive mind map at:
www.gogeometry.com/mindmap/darpa_mathematical_challenges_elearning.html

Elearn Geometry Problem 187

See complete Problem 187 at:
www.gogeometry.com/problem/p187_right_triangle_circle.htm

Right Triangle, Altitude, Incenters, Circles, Angles. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

Elearn Geometry Problem 186

See complete Problem 186 at:
www.gogeometry.com/problem/p186_right_triangle_circle.htm

Right Triangle, Altitude, Incenters, Circles. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.