The length of the base is given by the difference (absolute value) of the x coordinates of the two lower points, because it is a horizontal segment. So, the base length is
[tex] |4-(-3)| = 7 [/tex]
Similarly, the height is a vertical segment going from a quote of 9 to a quote of 1, so the length is
[tex] |9-1| = 8 [/tex]
So, the area is
[tex] A = \dfrac{bh}{2} = \dfrac{8\cdot 7}{2} = 4\cdot 7 = 28 [/tex]
