Question

Find the area of the triangle having vertices p(3, −1), q(3, 2), r(−3, −3).

Answer 1

See, please, the offered decision.

Answer 2

`\mathrm{\mathbf{Vertices}\ \to\ P(3,-1);\ Q(3,2);\ R(-3,-3)}\\\\ \mathrm{S=(1)/(2)|D|\ \to\ S=(1)/(2)\left|\begin{array}{ccc}\mathrm{x_P}&\mathrm{y_P}&1\\\mathrm{x_Q}&\mathrm{y_Q}&1\\\mathrm{x_R}&\mathrm{y_R}&1\end{array}\right|\ \to\ S=(1)/(2) \left|\begin{array}{ccc}3&-1&1\\3&2&1\\-3&-3&1\end{array}\right|\ \to}\\\\\\ \mathrm{\to\ S=(1)/(2)\big(6+3-9+3+9+3)\ \to\ \boxed{\mathbf{S=(15)/(2)\ u.a.}}}`