15. What are similar triangles?

16. How are similar triangles proportioned to each other?

17. The sides of a polygon being prolonged, what is the sum of all the
exterior angles equal to?

18. How do you pass the circumference of a circle through three given
points not in the same straight line?

19. How do you describe a square in a circle?

[Illustration]

20. In the triangle, b being a right angle, what proportion does d b
bear to a d and d c?

21. How do you inscribe a regular hexagon in a circle?

22. What proportion do circumference and areas of circles bear to
their radii?

23. How do you find the area of a regular polygon?

24. Of an irregular polygon?

25. Of a circle?

26. How do you find the solid contents of a cylinder?