Answer:
12
Explanation:
The Pythagorean theorem is
a^2+b^2 = c^2 where a and b are the sides and c is the hypotenuse ( the side opposite the right angle)
a^2 + b^2 = c^2
Substitute the known values
5^2 + b^2 = 13^2
25+b^2 = 169
Subtract 25 from each side
25+b^2-25 =169-25
b^2 = 144
Take the square root of each side
sqrt(b^2) = sqrt(144)
b=12