研习自：[url=https://www.bilibili.com/video/BV1De4y1a7z7/?spm_id_from=333.337.search-card.all.click&vd_source=edcad05029f6d4b15eaba8a422397416]【GGB教学】（指令）折线图7-绘制圆台_哔哩哔哩_bilibili[/url][br][br][url=https://www.bilibili.com/video/BV1WP411V7C2/]【GGB教学】（指令）折线图13-圆锥圆柱圆台在平面上的正投影_哔哩哔哩_bilibili[/url]