You can "play" with the sketch by using the arrow to select key points on the sketch and move them around. When you close the sketch, you have the option to save the sketch. If you choose to do so, please place the sketch in your folder so that you can find it again in the future.

1. Centroid: The Centroid is the point of concurrence of the 3 medians (segment from vertex to midpoint of opposite side).

2. Orthocenter: The Orthocenter is the point of concurrence of the three lines containing the altitudes of the triangle.

3. Circumcenter: The Circumcenter (C) is the point in the plane equidistant from the 3 vertices. Therefore C lies on the perpendicular bisectors of each side of the triangle.

4. Circumcircle: The Circumcircle is the circle containing the vertices of a triangle. Its center is the Circumcenter of the triangle

5. Incenter: The Incenter (I) is the point on the interior of the triangle equidistant from the 3 sides. I is the point of coincidence of the angle bisectors of the 3 angles of the triangle

6. Incircle: The Incircle is the inscribed circle of the triangle. The incenter is the center of the Incircle.

7. Medial Triangle 1: The Medial Triangle is formed by connecting the midpoints of the sides of a triangle.

7a. Medial Triangle 2: Medial Triangle is constructed independent of the original triangle

7b. Orthocenter, Mid-segment triangle: The triangle formed by connecting the midpoints of the segments between the vertices and the orthocenter of a triangle.

8. Orthic triangle: In an acute triangle, the Orthic triangle is formed by connecting the feet of the altitudes

9. Pedal triangle: Given any triangle ABC, locate any point P in the plane. Form a triangle by constructing perpendiculars to the sides of ABC (extended if necessary) locate three points R, S, and T that are the intersections. Triangle RST is the Pedal Triangle.

10. Center of Nine point circle:

12. Nine Point Circle: The Nine Point Circle is formed from the midpoints of the sides of a triangle, the feet of the altitudes to each side, and the 3 midpoints of the segment from the vertices to the orthocenter.

14. Equilateral triangle, given a side

16. Isosceles triangle, given base and altitude

17. Triangle Centers (H, G, C, and I): Orthocenter (H), Centroid (G), Circumcenter, and Incenter.

18. Triangle Centers with Euler Line: (line through Orthocenter, Centroid, and Circumcenter)

19. Sierpinski's Triangle: Fractal design created by multiple iterations of the medial triangle of an equilateral triangle

20. Angle Bisector of Disjoint Segments:

21. Half the Area of a Triangle: Given any triangle, construct a segment parallel to the base that divides the triangle into two equal areas.

22. Hidden Treasure:

23. Pentagon given radius: (needs work)

24. Square given radius: