Step-by-step explanation:
[tex]Slope \: of \: AB = \frac{1 - 1}{7 - 2} = \frac{0}{5} = 0 \\ \\ Slope \: of \: BC = \frac{4 - 1}{2 - 7} = \frac{3}{ - 5} = - \frac{3}{ 5} \\ \\ \because \: Slope \: of \: AB \neq \: Slope \: of \: BC \\ \\ \therefore \: given \: points \: are \: non - collinear. \\[/tex]
Hence, coordinates A(2, 1), B(7, 1), C(2, 4) form a triangle.
