Xianjing park has a circular fountain with a diameter of 12 meters. There is a circle of stainless steel guardrail 0.5 meters outside the fountain. What is the minimum length of the guardrail If you want to work out the formula, you have to say the truth

Xianjing park has a circular fountain with a diameter of 12 meters. There is a circle of stainless steel guardrail 0.5 meters outside the fountain. What is the minimum length of the guardrail If you want to work out the formula, you have to say the truth

3.14×(12+0.5×2)
=3.14×13
=40.82 M