Final answer:
The functions that describe the altitude and base of the triangle are 'Altitude = 2b + 4' and 'Base = b'. The area function of the banner is 'Area = b^2 + 2b'.
Step-by-step explanation:
To define the functions that describe the altitude and base of the triangle, let's assume the base of the triangle is 'b' feet. According to the problem, the altitude is 4 feet longer than twice its base, so the altitude can be expressed as '2b + 4' feet. Therefore, the functions that describe the altitude and base of the triangle are:
Altitude = 2b + 4
Base = b
To build the area function of the banner, we can use the formula for the area of a triangle which is 1/2 × base × altitude. Substituting the functions for base and altitude into the area formula, we get:
Area = 1/2 × b × (2b + 4)
Expanding and simplifying the expression, we have:
Area = b^2 + 2b