Given the sides of a triangular rug and an included angle between them, the area is calculated through the equation,
A = 0.5ab (cos C)
where a and b are the lengths of the side and C is the included angle.
A = 0.5(5 ft)(4 ft)(cos 79°)
A = 1.9 ft²
Thus, the area of the triangular rug is approximately 1.9 ft².