Pls I need help this

Answer:
the third side is 4.
Step-by-step explanation:
Using Pythagorean theorem of a^2 + b^2 = c^2 for right triangles, substitute
the numbers to show ([tex]\sqrt{65})^{2}[/tex] + [tex]b^{2}[/tex] = [tex]9^{2}[/tex] and solve for b. The square root and square cancel each other out, so you get 65 + [tex]b^{2}[/tex] = 81.
Subtract 65 from both sides to get [tex]b^{2}[/tex] = 16.
Then take the square root of both sides to get b = [tex]\sqrt{16}[/tex] which equals 4.