Answer 1

64
Number of straight lines joining 12 points if we take 2 points at a time = ¹²C₂

\[= \frac{12!}{2! 10!} = 66\]
Number of straight lines joining 3 points if we take 2 points at a time = ³C2 = 3
But, 3 collinear points, when joined in pairs, give only one line.
∴ Required number of straight lines =\[66 - 3 + 1 = 64\]