Proof of the Pythagorean Theorem using similarity Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/geometry/right_triangles_topic/pythagorean_proofs/e/pythagorean-theorem-proofs?utm_source=YT&utm_medium=Desc&utm_campaign=Geometry Watch the next lesson: https://www.khanacademy.org/math/geometry/right_triangles_topic/pythagorean_proofs/v/another-pythagorean-theorem-proof?utm_source=YT&utm_medium=Desc&utm_campaign=Geometry Missed the previous lesson? https://www.khanacademy.org/math/geometry/right_triangles_topic/pythagorean_proofs/v/bhaskara-s-proof-of-pythagorean-theorem-avi?utm_source=YT&utm_medium=Desc&utm_campaign=Geometry ... https://www.youtube.com/watch?v=LrS5_l-gk94 Note: All Khan Academy content is available for free at (www.khanacademy.org)

Kim talks about how to analyze the documents in the document-based question section of the AP US history exam. Watch the next lesson: https://www.khanacademy.org/humanities/us-history/historians-toolkit/apush-practice/v/ap-us-history-dbq-example-3?utm_source=YT&utm_medium=Desc&utm_campaign=UShistory Missed the previous lesson? https://www.khanacademy.org/humanities/us-history/historians-toolkit/apush-practice/v/ap-us-history-dbq-example-1?utm_source=YT&utm_medium=Desc&utm_campaign=UShistory US history on Khan Academy: From a mosquito-ridden backwater to the world's last remaining superpower, the United States of America is a nation with a rich history and a noble goal: government of the people, by the people, for the people. Its citizens' struggle to achieve that goal is a dramatic story stretching over hundreds of years. About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. ... https://www.youtube.com/watch?v=vPnKHpi8cYE Note: All Khan Academy content is available for free at (www.khanacademy.org)

Scalene, isosceles, equilateral, acute, right, obtuse. All are types of triangles but what makes them special depends on the method of categorization. Watch this outstanding explanation. Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-geometry-topic/cc-4th-classifying-triangles/e/recognizing-triangles?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Watch the next lesson: https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-geometry-topic/cc-4th-classifying-triangles/v/scalene-isosceles-equilateral-from-angle?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Missed the previous lesson? https://www.khanacademy.org/math/cc-fourth-grade-math/cc-4th-geometry-topic/cc-4th-classifying-quadrilaterals/v/quadrilateral-types-exercise?utm_source=YT&utm_medium=Desc&utm_campaign=4thgrade Grade 4th on Khan Academy: 4th grade is the time to start really fine-tuning your arithmetic skills. Not only will you be a multi-digit addition and subtraction rockstar, but you'll extend the multiplication and division that you started in 3rd grade to several digits. You'll also discover that you sometimes have something left over (called a "remainder") when you divide. In 3rd grade you learned what a fraction is. Now you'll start adding, subtracting, multiplying, and comparing them. You'll also see how they relate to decimals. On other fronts, you'll learn how to convert between different units (which is super important when comparing the size and speed of robot unicorns in different countries) and continue your journey thinking about various shapes in two dimensions. Some of the foundational concepts of geometry (like lines, rays and angles) also get introduced. As always, we'll round this out with a healthy dose of applied word problems and explorations of number patterns and properties (including the ideas of factors, multiples and prime numbers). The fun must not stop! (Content was selected for this grade level based on a typical curriculum in the United States.) ... https://www.youtube.com/watch?v=D5lZ3thuEeA Note: All Khan Academy content is available for free at (www.khanacademy.org)

(Ax+By)(Ax+By) More free lessons at: http://www.khanacademy.org/video?v=Sc0e6xrRJYY https://www.youtube.com/watch?v=Sc0e6xrRJYY