Using Pythagorean theorem c^2=a^2 + b^2, we can find the missing side b.
Put values in equation.
18^2 = 8^2 + b^2
324=64+b^2
Subtract 64 from both sides
260= b^2
Take square root.
2√65=b
or
b=16.12
Answer: b=2√65 Radical form. or b=16.12 Decimal form.