Proof - Triangle Altitudes are Concurrent (Orthocenter) Showing that any triangle can be the medial triangle for some larger triangle. Using this to show that the altitudes of a triangle are concurrent (at the orthocenter).
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Tags: Proof - Triangle Altitudes are Concurrent (Orthocenter)
Uploaded by: khangeometry ( Send Message ) on 06-09-2012.
Duration: 10m 1s
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Lec 1 - Euclid as the Father of Geometry
Lec 2 - Language and Notation of Basic Geometry
Lec 3 - Lines, Line Segments, and Rays
Lec 4 - Language and Notation of the Circle
Lec 6 - Measuring Angles in Degrees
Lec 9 - Complementary and Supplementary Angles
Lec 10 - Angles at the intersection of two lines
Lec 11 - Proof-Vertical Angles are Equal
Lec 12 - Angles Formed by Parallel Lines and Transversals
Lec 13 - Proof - Sum of Measures of Angles in a Triangle are 180
Lec 14 - Triangle Angle Example 1
Lec 15 - Triangle Angle Example 2
Lec 16 - Triangle Angle Example 3
Lec 17 - Challenging Triangle Angle Problem
Lec 18 - Proof - Corresponding Angle Equivalence Implies Parallel Lines
Lec 20 - Sum of Interior Angles of a Polygon
Lec 21- Congruent Triangles and SSS
Lec 22 - SSS to Show a Radius is Perpendicular to a Chord that it Bisects
Lec 23 - Other Triangle Congruence Postulates
Lec 24 - Two column proof showing segments are perpendicular
Lec 25 - Sum of the exterior angles of convex polygon
Lec 26 - Finding Congruent Triangles
Lec 27 - More on why SSA is not a postulate
Lec 28 - Congruent Triangle Proof Example
Lec 29 - Congruent Triangle Example 2
Lec 30 - Congruent legs and base angles of Isosceles Triangles
Lec 31 - Equilateral Triangle Sides and Angles Congruent
Lec 32- Equilateral and Isosceles Example Problems
Lec 33 - Another Isosceles Example Problem
Lec 34 - Example involving an isosceles triangle and parallel lines
Lec 35 - Figuring out all the angles for congruent triangles example
Lec 36 - Perimeter and Area Basics
Lec 38 - Interesting Perimeter and Area Problems
Lec 39 - Koch Snowflake Fractal
Lec 40 - Area of an Equilateral Triangle
Lec 41 - Area of Koch Snowflake (part 1) - Advanced
Lec 42 - Area of Koch Snowflake (part 2) - Advanced
Lec 43 - Challenging Perimeter Problem
Lec 44 - Similar Triangle Basics
Lec 45 - Similarity Postulates
Lec 46 - Similar Triangle Example Problems
Lec 47 - Similarity Example Problems
Lec 48 - Challenging Similarity Problem
Lec 49 - Similarity example where same side plays different roles
Lec 50 - Finding Area Using Similarity and Congruence
Lec 51 - Pythagorean Theorem Proof Using Similarity
Lec 52 - 30-60-90 Triangle Side Ratios Proof
Lec 53 - 45-45-90 Triangle Side Ratios
Lec 54 - 30-60-90 Triangle Example Problem
Lec 56 - Introduction to angles (old)
Lec 59 - Angles formed between transversals and parallel lines
Lec 60 - Angles of parallel lines 2
Lec 63 - Similar triangles (part 2)
Lec 65 - Acute Right and Obtuse Angles
Lec 67 - Circles: Radius, Diameter and Circumference
Lec 69 - The Pythagorean Theorem
Lec 70 - Pythagorean Theorem II
Lec 72 - Intro to 30-60-90 Triangles
Lec 73 - 30-60-90 Triangles II
Lec 74 - Solid Geometry Volume
Lec 75 - Cylinder Volume and Surface Area
Lec 77 - Part 1 of Proof of Heron's Formula
Lec 78 - Part 2 of the Proof of Heron's Formula
Lec 79 - Inscribed and Central Angles
Lec 80 - Area of Inscribed Equilateral Triangle (some basic trig used)
Lec 81 - Right Triangles Inscribed in Circles (Proof)
Lec 82 - Area of Diagonal Generated Triangles of Rectangle are Equal
Lec 83 - Triangle Medians and Centroids
Lec 84 - Triangle Medians and Centroids (2D Proof)
Lec 86 - 2003 AIME II Problem 7
Lec 87 - Perpendicular Radius Bisects Chord
Lec 88 - Circumcenter of a Triangle
Lec 89 - Circumcenter of a Right Triangle
Lec 90 - Three Points Defining a Circle
Lec 91 - Point Line Distance and Angle Bisectors
Lec 92 - Incenter and incircles of a triangle
Lec 93 - Angle Bisector Theorem Proof
Lec 94 - Inradius Perimeter and Area
Lec 95 - Angle Bisector Theorem Examples
Lec 96 - Medians divide into smaller triangles of equal area
Lec 97 - Exploring Medial Triangles
Lec 98 - Proving that the Centroid is 2-3rds along the Median