Contact us
Choose a category below so we can get back to you as quickly as possible.
外圓直徑10釐米,半徑5釐米 內圓直徑6釐米,半徑3釐米 鐵片面積是 π×5×5-π×3×3≈50.24平方釐米
We and our partners use cookies and other technologies to analyze traffic and optimize your experience. View more info and control your cookies settings at any time in our Cookies Policy.