Answer:
12 inches
Step-by-step explanation:
We are using the Pythagorean theorem
a^2 +b^2 = c^2
The diagonal is c, or the hypotenuse
16^2 + b^2 = 20^2
256 + b^2 = 400
Subtract 256 from each side
256+b^2 -256 = 400-256
b^2 =144
Take the square root of each side
sqrt(b^2) = sqrt(144)
b = 12
