Pythagoras was a Greek mathematician, teacher and philosopher. He had his own theory which was obviously called the "Pythagoras Theory."
Right Angle Triangle.
A right angle triangle has one 90 degree angle. On the second picture you see the symbols Q and B. The Q is called theta, and the B is called beta. The symbol is there because it means that the angle degree is going to equal to 90 when you have two of it. But the two angles don't have to equal the same they could be different as long as the angles equal 90 degrees. The letter A and the purple B are called the legs. The purple C is the hypotenuse. The hypotenuse is the longest side of a triangle.
Squares and Rectangles
The picture above is a square and a rectangle. The lines on the square means that the dimensions are all equal. The lines in the rectangle have two ticks, and the other two sides have only one. That means that the two parallel sides are the same.
The picture above is an example on how the problem looks like.
a² + b² = c²
you have to replace the letters into numbers
8² + b² = 10²
now we have to figure out what b equals
we now have to find the square root of 36
you think we are finished but we aren't because there was two triangles. We now have to add 6+6. It equals 12 so b equals 12. Also don't forget the meter value.
(The pictures above were taken from Mr. H's blog)