We are given vertices of a rectangle (0, −4) , (−1, −3) , (2, 0) , and (3, −1).
Length is the distance between (0, −4) and (−1, −3) points.
Width is distance between (−1, −3) and (2, 0) points.
Computing length:
[tex]\mathrm{Compute\:the\:distance\:between\:}\left(x_1,\:y_1\right),\:\left(x_2,\:y_2\right):\quad \sqrt{\left(x_2-x_1\right)^2+\left(y_2-y_1\right)^2}[/tex]
[tex]=\sqrt{\left(-1-0\right)^2+\left(-3-\left(-4\right)\right)^2}[/tex]
[tex]=\sqrt{2}[/tex]
Computing Width :
[tex]\mathrm{The\:distance\:between\:}\left(-1,\:-3\right)\mathrm{\:and\:}\left(2,\:0\right)\mathrm{\:is\:}[/tex]
[tex]=\sqrt{\left(2-\left(-1\right)\right)^2+\left(0-\left(-3\right)\right)^2}[/tex]
[tex]=3\sqrt{2}[/tex]
= [tex]\sqrt{2} \times 3\sqrt{2} = 3 \times 2 = 6 \ squares \ units.[/tex].