In the above diagram, the 16 dots are in rows and columns,

GMAT/MBA Expert

Mike@Magoosh: GMAT Instructor; Posts: 768; Joined: Wed Dec 28, 2011 4:18 pm; Location: Berkeley, CA; Thanked: 387 times; Followed by:140 members

by Mike@Magoosh » Mon Feb 03, 2014 10:53 am

In the diagram above, the 16 dots are in rows and columns, and are equally spaced in both the horizontal & vertical direction. How many triangles, of absolutely any shape, can be created from three dots in this diagram? Different orientations (reflections, rotations, etc.) and/or positions count as different triangles. (Notice that three points all on the same line cannot form a triangle; in other words, a triangle must have some area.)
(A) 516
(B) 528
(C) 1632
(D) 3316
(E) 3344

Many GMAT math problems, such as this one, cannot be solved simply by formulas you have memorized. Yes, formulas are useful, but alone, formulas will not get you through the GMAT Quant section. For a discussion of the uses & abuses of formulas, as well as the OA & OE of this particular question, see:
https://magoosh.com/gmat/2014/gmat-math- ... -formulas/

Mike

Magoosh GMAT Instructor
https://gmat.magoosh.com/

Quote