Answer:
B
Step-by-step explanation:
The Pythagoras theorem states that [tex]c^{2} = a^{2} + b^{2[/tex], where [tex]c[/tex] is the hypotenuse and a and b are the adjacent and opposite sides of the hypotenuse. If we made [tex]a[/tex] the subject of the expression, the expression will be re-written as [tex]a^{2} = c^{2} - b^{2}[/tex], which is the correct answer.