Eighteen dots are evenly spaced on the circumference of a circle. How many combinations of three dots can we make from these 18 dots that do not form an equilateral triangle?	Options: A) 792 B) 798 C) 804 D) 810 E) 816
The total number of ways we can choose three dots is 18C3=816.   We can form six equilateral triangles from these eighteen dots.   There are  816 - 6= 
<gadget id="calculator"> 816 - 6</gadget>
<output>810</output>
810 combinations which do not form an equilateral triangle.   The answer is 810.
<result>D</result>
Eighteen dots are evenly spaced on the circumference of a circle. How many combinations of three dots can we make from these 18 dots that do not form an equilateral triangle?