The formula for the surface area of a triangular pyramid is:
Surface Area = (0.5 * base perimeter * slant height) + (base area)
First, let's calculate the base perimeter:
Base perimeter = 3 * side = 3 * 4.5 cm = 13.5 cm
Now, let's calculate the base area of an equilateral triangle:
Base area = (sqrt(3)/4) * side^2 = (sqrt(3)/4) * (4.5^2) = (sqrt(3)/4) * 20.25 = 8.78 cm^2
Now, plug in the values into the formula to find the surface area:
Surface Area = (0.5 * 13.5 * 3.5) + 8.78
Surface Area = 23.625 + 8.78
Surface Area = 32.405 cm^2
Therefore, the surface area of the triangular pyramid with an equilateral triangle base is 32.405 cm^2.