铜线直径和截面积

　　参考：https://item.taobao.com/item.htm?id=623727433358&ali_refid=a3_420434_1006:1452580068:N:DHKXWETh%2Fn0PiivD%2B%2FT9lEX2coIxvVAZ:d0ea01000897b89eba2121dc1db92ae6&ali_trackid=1_d0ea01000897b89eba2121dc1db92ae6&spm=a230r.1.1957635.41