Answer:
a=3
Step-by-step explanation:
Since this is a right triangle, we can use the Pythagorean theorem
a^2+b^2 = c^2 where a and b are the legs and c is the hypotenuse
a^2+4^2 = 5^2
a^2 +16 = 25
a^2 =25-16
a^2 = 9
Taking the square root of each side
sqrt(a^2) = sqrt(9)
a =3
