How can the pythagorean theorem be used to solve problems?

Pythagoras theorem The thing I hate the most..
In a traingle if you know two if its sides ( we say A and B ) you square them and get the third side C .
You didn't understand.
Let me explain.
We have a triangle, one side is 4cm other is 3cm how do you find the third side?
Yes, Pythagoras theorem.
That is a^2 + b^2 = c^2.
You square 4 and 3:
That will be 16 and 9 then you add them.
16+9= 25 find the root of 25 that is 5.
You get the third side as 5cm.
That's how you use Pythagoras theorem.