Theorems in plane geometry | Foundations of geometry | Euclidean plane geometry
In geometry, the crossbar theorem states that if ray AD is between ray AC and ray AB, then ray AD intersects line segment BC. This result is one of the deeper results in axiomatic plane geometry. It is often used in proofs to justify the statement that a line through a vertex of a triangle lying inside the triangle meets the side of the triangle opposite that vertex. This property was often used by Euclid in his proofs without explicit justification. Some modern treatments (not Euclid's) of the proof of the theorem that the base angles of an isosceles triangle are congruent start like this: Let ABC be a triangle with side AB congruent to side AC. Draw the angle bisector of angle A and let D be the point at which it meets side BC. And so on. The justification for the existence of point D is the often unstated crossbar theorem. For this particular result, other proofs exist which do not require the use of the crossbar theorem. (Wikipedia).
The vector cross-product is another form of vector multiplication and results in another vector. In this tutorial I show you a simple way of calculating the cross product of two vectors.
From playlist Introducing linear algebra
Proof: The Angle Bisector Theorem
This video states and proves the angle bisector theorem. Complete Video List: http://www.mathispower4u.yolasite.com
From playlist Relationships with Triangles
The Cross law in Universal Hyperbolic Geometry | Universal Hyperbolic Geometry 28 | NJ Wildberger
The Cross law is the fourth of the four main laws of trigonometry in the hyperbolic setting. It is also the most complicated, and the most powerful law. This video shows how we can prove it with the help of a remarkable polynomial identity. We also give an application to the relation betwe
From playlist Universal Hyperbolic Geometry
What is the Alternate Exterior Angle Converse Theorem
👉 Learn about converse theorems of parallel lines and a transversal. Two lines are said to be parallel when they have the same slope and are drawn straight to each other such that they cannot meet. In geometry, parallel lines are identified by two arrow heads or two small lines indicated i
From playlist Parallel Lines and a Transversal
Ex 2: Properties of Cross Products - Cross Product of a Sum and Difference
This video explains how to find the cross product of a sum and difference of two vectors. Site: http://mathispower4u.com
From playlist Vectors in Space (3D)
What is the Corresponding Angle Converse Theorem
👉 Learn about converse theorems of parallel lines and a transversal. Two lines are said to be parallel when they have the same slope and are drawn straight to each other such that they cannot meet. In geometry, parallel lines are identified by two arrow heads or two small lines indicated i
From playlist Parallel Lines and a Transversal
The Perfect Goal Kicking Angle - Numberphile
Ben Sparks reveals the formula for optimal goal kicking... See https://brilliant.org/numberphile for Brilliant and 20% off their premium service & 30-day trial (episode sponsor)... More links & stuff in full description below ↓↓↓ This is based on the sport of Rugby Union. The principles c
From playlist Ben Sparks on Numberphile
Multivariable Calculus: Cross Product
In this video we explore how to compute the cross product of two vectors using determinants.
From playlist Multivariable Calculus
Multivariable Calculus | The Cross Product
We define the cross product, give a few examples, and state a few properties. http://www.michael-penn.net http://www.randolphcollege.edu/mathematics/
From playlist Vectors for Multivariable Calculus
An introduction to group (and Galois) cohomology (part 2)
This is part 2 of an introduction to group (and Galois) cohomology, with a particular emphasis on the applications to the cohomology of fields, and elliptic curves.
From playlist An Introduction to the Arithmetic of Elliptic Curves
Quadratic Formula Derivation and Application to Penalty Kicks & Archery
In celebration of Maths Week London, University of Oxford mathematician Dr Tom Crawford derives the quadratic formula using the method of 'completing the square' and then applies it to solve real-world problems in football and archery. We start with some examples demonstrating the method
From playlist Special Events and Livestreams
Proving Parallel Lines with Angle Relationships
👉 Learn about converse theorems of parallel lines and a transversal. Two lines are said to be parallel when they have the same slope and are drawn straight to each other such that they cannot meet. In geometry, parallel lines are identified by two arrow heads or two small lines indicated i
From playlist Parallel Lines and a Transversal
DIY Roof Rack: Design, Construction, and Field Testing
In this video we show how to build your own roof rack for your car or van. I built this rack out of super strut (AKA unistrut) and mounted it to my 2015 Ford Transit van (148” wheelbase, medium roof). The roof rack cost approximately $360 and 24 hours of labor to construct. You can see
From playlist Adventure Van
1982 "Telephone Exchange" Origins of Electronic Switching Technology (telecom; central office)
Vintage 1982: This Excellent Telephone History documentary describes the development of telephone switching technology and the evolution of the "Telephone Exchange." A British Telecom educational film. (Slightly edited from the original, run time 17 mins.) A “TELEPHONE EXCHANGE” is a te
From playlist Vintage Telephone; AT&T; Bell Labs; Telecommunications; Satellites:
World Cup Fail: the science of Lampard's 'goal'
Who needs goal-line technology when you have physics? Watch as Andy explains how a little bit of physics could've proved that Lampard's disallowed 2010 world cup goal went in. Click here to subscribe for more science videos: http://bit.ly/RiSubscRibe In a crucial World Cup 2010 knock-out
From playlist Tales from the Prep Room
Determine the sides of a triangle produce an acute, obtuse or right triangle
Learn about the Pythagorean theorem. The Pythagoras theorem is a fundamental relation among the three sides of a right triangle. It is used to determine the missing length of a right triangle. The Pythagoras theorem states that the square of the hypotenuse (the side opposite the right angl
From playlist Geometry - PYTHAGOREAN THEOREM
In high school physics there are many opportunities to use soccer to spark students’ interest in studying the laws of energy and motion. Projectile motion, conservation of energy, Newtons laws of motion, and the Magnus effect are just a few of the topics that soccer players unknowingly use
From playlist Kinematics; Two Dimensional Projectile Motion
How To Determine If Two Lines are Parallel to Apply Angle Theorems
👉 Learn about converse theorems of parallel lines and a transversal. Two lines are said to be parallel when they have the same slope and are drawn straight to each other such that they cannot meet. In geometry, parallel lines are identified by two arrow heads or two small lines indicated i
From playlist Parallel Lines and a Transversal
How It's Made: Metal Bistro Sets
Learn how metal bistro sets are made! Stream Full Episodes of How It's Made: https://www.sciencechannel.com/tv-shows/how-its-made/ Subscribe to Science Channel: http://bit.ly/SubscribeScience Like us on Facebook: https://www.facebook.com/ScienceChannel Follow us on Twitter: https://tw
From playlist How It's Made