You can put this solution on YOUR website! Open the Insert tab.
You should see at the right-hand end of the ribbon, the Symbols group.
Left-click the Equation item, which has a symbol with it.
Type your equation, in your case, Pythagorean Theorem Formula, and try doing it in pure text.
Click outside but next-to the box which contains the equation you just entered, and your equation should now appear in the document.
I had to give a space using the spacebar after entering the exponent on the c variable in order for the correct typesetting to occur.
You must put the equation in like THIS in pure text:
a^2+b^2=c^2
and then the space using the space bar;
and then click outside of the input field.