CAD练习题9——较为复杂的利用圆作固定角度三角形

题目:

https://github.com/longlongpicture/myblogpicture/raw/master/p9-12.PNG

这道题看上去较为复杂,但实际上还是利用圆作固定角度三角形。

1、画出明显已知的部分。

https://github.com/longlongpicture/myblogpicture/raw/master/p9-1.PNG

2、画出下半部分的90度。

https://github.com/longlongpicture/myblogpicture/raw/master/p9-2.PNG

3、作等分和旋转作垂线。

https://github.com/longlongpicture/myblogpicture/raw/master/p9-3.PNG

4、先处理右侧的72度,由于顶角是72度,所以作一条18度的斜线和过基线中点的垂线,以相交的点为圆心画圆。

https://github.com/longlongpicture/myblogpicture/raw/master/p9-4.PNG

5、上一步的圆与最右侧垂线交于一点,连接三点,得到72度顶角。

https://github.com/longlongpicture/myblogpicture/raw/master/p9-5.PNG

6、同样原理,得到其他三个角,注意每次基线长度是不同的。

https://github.com/longlongpicture/myblogpicture/raw/master/p9-6.PNGhttps://github.com/longlongpicture/myblogpicture/raw/master/p9-7.PNGhttps://github.com/longlongpicture/myblogpicture/raw/master/p9-8.PNGhttps://github.com/longlongpicture/myblogpicture/raw/master/p9-9.PNGhttps://github.com/longlongpicture/myblogpicture/raw/master/p9-10.PNGhttps://github.com/longlongpicture/myblogpicture/raw/master/p9-11.PNG

7、清理图形。

https://github.com/longlongpicture/myblogpicture/raw/master/p9-12.PNG