Hey there!
To start, the Pythagorean Theorem is a²+b²=c² where a and b are the two legs of a right triangle (the sides that aren't the hypotenuse) and c is the hypotenuse.
In the case you need to find side a, first isolate a² in which you do so by subtracting b² from both sides and finding the square root of both sides:
a² = c²- b²
a = [tex]\sqrt{c^{2}-b^{2} }[/tex]
As for finding side b, you do the same:
b² = c² - a²
b = [tex]\sqrt{c^{2}-a^{2} }[/tex]
To find side c (the hypotenuse), find the square root of both sides:
c = [tex]\sqrt{a^{2}+b^{2} }[/tex]
Hope this helps!
