In his Essential Geometry Techniques series, Part 2, Greg mentions an important formula to calculate number of possible diagonals in a polygon.
I have gone through all of the PrepSwift videos and nowhere is that mentioned – I am relying on PrepSwift for my Quant foundation, so I’m pretty surprised that this is the second concept that is missing from the material (Sequences being the other).
Is there a question you have? You can easily derive the formula (even if non-rigorously) with pattern recognition.
Here’s an exercise for you to “think about” a formula for the number of diagonals.
This is not something I think needed to be explicitly covered - what was shown above was part of an ETS problem actually, so it’s not a “concept”.
Interesting, as Greg clearly mentions it in his geometry essentials video and also says there is a formula (n-3) x n / 2
And this exact concept is then tested in the #1 Geometry Foundation Quiz once again…
