Gradient of AB = \(\frac{y_2-y_1}{x_2-x_1} = \frac{4-(-1)}{4-(-3)} = \frac{4+1}{4+3} =5/7\)
Since AB and BC forms a right angle, this means that AB and BC are perpendicular.
For perpendicular lines, m2 = -1/m1; where m1 and m2 are the gradient of the two lines.
i.e. m2 = -1/(5/7) = -7/5
Therefore, the equation of BC is given by
\(\frac{y-y_1}{x-x_1} =m_2 \\ \frac{y-4}{x-4} = -\frac{7}{5} \\ 7(x-4)=-5(y-4) \\ 7x-28=-5y+20 \\ -7x-5y=-48\)
