Twelve dots are evenly spaced on the circumference of a circle. How many combinations of three dots can we make from these 12 dots that do not form an equilateral triangle? Choose one:
A) 208
B) 212
C) 216
D) 220
E) 224
The total number of ways we can choose three dots is 12C3=220.   We can form four equilateral triangles from these twelve dots.   There are  220 - 4= 
<gadget id="calculator"> 220 - 4</gadget>
<output>216</output>
216 combinations which do not form an equilateral triangle.   The answer is 216.
<result>C</result>
Twelve dots are evenly spaced on the circumference of a circle. How many combinations of three dots can we make from these 12 dots that do not form an equilateral triangle?