In the triangle ABC with vertices A(2,3), B(4,-1) and C(1,2), find the equation and length of altitude from the vertex A.

Question

$\begin{array}{1 1}(A)\;\text{equation} = x-y=1 \: \text{and length is } \sqrt 2\: \text{units} \\(B)\; \text{equation} = x+y=1 \text{and length is } 2\: \text{units} \\(C)\; \text{equation} = -x+y+1=0 \: \text{and length is } 2\sqrt 2 \text{ units} \\(D)\;\text{equation} = x-y=-1 \text{ and length is } \large\frac{1}{\sqrt 2} \text{ units} \end{array} $