Assuming the lines are not parallel and coinciding. So a similar to this;
So with those four coordinates only, how to find (a,b)
Assuming the lines are not parallel and coinciding. So a similar to this;
So with those four coordinates only, how to find (a,b)
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The equation of the first line is $$ y - y_1 = \frac{y_2 - y_1}{x_2-x_1}\left(x - x_1 \right) $$ and similarly of the second line is $$ y - y_3 = \frac{y_4 - y_3}{x_4-x_3}\left(x - x_3 \right) $$ equating $y$-values at the intersection point gives us the linear equation in $x$ $$y_1 + \frac{y_2 - y_1}{x_2-x_1}\left(x - x_1 \right) = y_3 + \frac{y_4 - y_3}{x_4-x_3}\left(x - x_3 \right) $$ Can you take it from here?