A Triangle with Vertices at (X1, Y1), (X2, Y2), and (X3

Multiple Choice

A triangle with vertices at (x1, y1) , (x2, y2) , and (x3, y3) has area equal to the absolute value of D, where $$D = \frac { 1 } { 2 } \left| \begin{array} { l l l } x _ { 1 } & y _ { 1 } & 1 \\x _ { 2 } & y _ { 2 } & 1 \\x _ { 3 } & y _ { 3 } & 1\end{array} \right|$$ Find the area of the triangle having vertices at P, Q, and R.
- $P ( 0 , - 4 ) , Q ( 0,5 ) , R ( 5,1 )$

A) 3
B) 45
C) $\frac { 45 } { 2 }$
D) 0