Area of triangle = base x height x 1/2
18 = (x - 1) • (x + 4) • 1/2
18 • 2 = (x - 1) • (x + 4)
36 = (x - 1)(x + 4)
36 = (x² + 4x - 1x - 4)
36 = x² + 3x - 4
0 = x² + 3x - 4 - 36
x² + 3x - 40 = 0
(x + 8)(x - 5) = 0
x + 8 = 0 or x - 5 = 0
x = -8 or x = 5
“-8” is rejected, as length/width/height can’t be negative.
The length of the shortest side the triangle:
Short side = x - 1
= 5 - 1
= 4
