Lec 108 - Proof - Opposite Angles of Parallelogram Congruent

Lecture list for this course

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 5 - Angle Basics

Lec 6 - Measuring Angles in Degrees

Lec 7 - Using a Protractor

Lec 8 - Measuring Angles

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 19 - Finding more angles

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 37 - Triangle Area Proofs

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 55 - The Golden Ratio

Lec 56 - Introduction to angles (old)

Lec 57 - Angles (part 2)

Lec 58 - Angles (part 3)

Lec 59 - Angles formed between transversals and parallel lines

Lec 60 - Angles of parallel lines 2

Lec 61 - The Angle Game

Lec 62 - Similar triangles

Lec 63 - Similar triangles (part 2)

Lec 64 - Angle Game (part 2)

Lec 65 - Acute Right and Obtuse Angles

Lec 66 - Area and Perimeter

Lec 67 - Circles: Radius, Diameter and Circumference

Lec 68 - Area of a circle

Lec 69 - The Pythagorean Theorem

Lec 70 - Pythagorean Theorem II

Lec 71 - 45-45-90 Triangles

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 76 - Heron's Formula

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 85 - Rhombus Diagonals

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

Lec 99 - Median Centroid Right Triangle Example

Lec 100 - Proof - Triangle Altitudes are Concurrent (Orthocenter)