Use determinants to find the area of the triangle with vertices at the given points.
P(0, 0), Q(20, 0), R(20, 6)
a. A=20
b. A=60
c. A=120
d. A=6
e. none of these
Like so:
\(\text{area = } \frac{1}{2}\left| \begin{array}{rrrrr}0 & 0 & 1 \\ 20 & 0 & 1 \\ 20 & 6 & 1\end{array}\right| \\ \\ \text{area = } (0*(0*1 - 6*1) - 0*(20*1 - 20*1) + 1*(20*6 - 20*0))/2 \\ \\ \text{area = } 60 \\ \\ \)
