Answer:
a=4
Explanation:
In this problem, you would use Pythagorean Theorem which is
a² + b² = c²
a and b are legs and c is the hypotenuse. In this problem, a and 3 are the legs while 5 is the hypotenuse. So...
a=a
b=3
c=5
Now substitute the values into the equation
a²+3²=5²
Exponents
a²+9=25
Subtract 9 on both sides
a²= 16
Square root on both sides
√a²=√16
Simplify
a=4
Hope this helped!