Answer:
b=16
Explanation:
the Pythagorean theorem states that a² + b² = c²
you are looking for b in this case so you need to change the formula a bit
a² + b² = c²
subtract a² to the other side
b²= c²-a²
now plug in the values
b²= 20²-12²
(the hypotenuse= the longest side or 20cm)
solve
b²= 400 - 144
b²= 256
take the square root of both sides
b = 16
check:
400 =144 + 256
400=400