## Basic College Mathematics (9th Edition)

Area of the shaded part = 54 ft$^{2}$
To find the area of the shaded portion we simply find the area of the entire triangle and subtract the area of the un-shaded square. Area of a Square: $A$$_{sqr} = s$$^{2}$ Therefore: $A$$_{sqr} = (3 ft)^{2} A$$_{sqr}$ = 9 ft$^{2}$ Area of a Triangle: $A$$_{tri} = \frac{1}{2}$$b$$h Therefore: A$$_{tri}$ = $\frac{1}{2}$(18 ft)(7 ft) $A$$_{tri} = 63 ft^{2} A$$_{total}$ = $A$$_{tri} - A$$_{sqr}$ Therefore: $A$$_{total}$ = 63 ft$^{2}$ - 9 ft$^{2}$ = 54 ft$^{2}$