100年前的生活妙招:如何画出完美的椭圆?
People don't often look back on the early 1900's for advice, but what if we could actually learn something from the Lost Generation? The New York Public Library has digitized 100 "how to do it" cards found in cigarette boxes over 100 years ago, and the tips they give are so practical that millennials reading this might want to take notes. How to Draw an Ellipse with String Size of ellipse having been determined, focuses are found by measuring off the short diameter(or width of ellipse) form ends of long diameter(or length of ellipse). Two pins should be fixed, and string or thread looped round, as shown in picture, Length of loop should be from A to B. |