8. Orthocenter, Mid-segment triangle.
11. Center of Nine point circle.
13. Trisecting a line segment.
14. Equilateral triangle, given a side.
16. Isosceles triangle, given base and altitude.
17. Triangle Centers (H, G, C, and I).
18. Triangle Centers with the Euler Line.
19. A circle tangent to two given circles.
20. Divide a segment AB into two parts that form a golden ratio.