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# Bhaskara's proof of the Pythagorean theorem

The 12th century Indian mathematician Bhaskara developed an elegant visual proof of the Pythagorean Theorem. Bhaskara uses a square and four congruent right triangles, rearranged in two ways, to prove this theorem. He shows that in a right triangle, the square of the longest side (hypotenuse) is equal to the sum of the squares of the other two sides. Created by Sal Khan.

## Want to join the conversation?

• How exactly did Sal cut the square into the 4 triangles? At time.
• He just picked an angle, then drew a line from each vertex across into the square at that angle. His angle choice was arbitrary. because as he shows later, he ends up with 4 identical right triangles. By just picking a random angle he shows that it works for any right triangle.
• How does the video above prove the Pythagorean Theorem?
• Think about the term "squared". That simply means a square with a defined length of the base. So when you see a^2 that just means a square where the sides are length "a". The same would be true for b^2. The Pythagorean theorem states that the area of a square with "a" length sides plus the area of a square with "b" sides will be equal to the area of a square with "c" length sides or a^2+b^2=c^2. Bhaskara simply takes his square with sides length "c" defines lengths for "a" and "b" and rearranges c^2 to prove that it is equal to a^2+b^2. Hope that helps. Watch the video again. :)
• Why in God's fair plains do I need to know this?
I simpler words can somebody please explain what he is doing? Much appreciated!
• When you understand how something was taught you may have a different perspective or even just a more of an appreciation for it (whether that appreciation may be the fact that you don't have to figure it out yourself or just the plain genius behind these thought experiments...)
Also you will prob need to learn to get through school and to be able to get a diploma which most jobs require....soo...
• why is it still a theorem if its proven? is there a difference between a theory and theorem?
• The word "theory" is not used in pure mathematics. "Theory" in science is the highest level of scientific understanding which is a thoroughly established, well-confirmed, explanation of evidence, laws and facts.

In pure mathematics, such as geometry, a theorem is a statement that is not self-evidently true but which has been proven to be true by application of definitions, axioms and/or other previously proven theorems.
• so many steps just to proof A2+B2=C2 it's too hard for me to try to remember all the steps
• You won't have to prove the Pythagorean theorem, the reason Sal runs through it here is to prove that we know that we can use it safely, and it's cool, and it strengthens your thinking process.
• So who actually came up with the Pythagorean theorem? Pythagoras, Bhaskara, or James Garfield?
• Again, you have to distinguish proofs of the theorem apart from the theorem itself, and as noted in the other question, it is probably none of the above.
• This is so cool what
• why dose he use theta and not like x?