The formula to find the surface area of a triangular pyramid is:
Surface Area = base area + lateral area
First, let's find the base area. The base is a triangle, so we can use the formula for the area of a triangle:
Base Area = (1/2) * base * height
In this case, the base is 3.9 cm and the height is the slant height, which is 3.5 cm. Plugging in these values into the formula, we get:
Base Area = (1/2) * 3.9 cm * 3.5 cm
= 6.825 cm^2
Next, let's find the lateral area. The lateral area consists of four congruent triangles, so we can use the formula for the area of a triangle:
Lateral Area = 4 * (1/2) * base * slant height
In this case, the base is 3.9 cm and the slant height is 3.5 cm. Plugging in these values into the formula, we get:
Lateral Area = 4 * (1/2) * 3.9 cm * 3.5 cm
= 27.3 cm^2
Finally, we can find the surface area by adding the base area and the lateral area:
Surface Area = base area + lateral area
= 6.825 cm^2 + 27.3 cm^2
= 34.125 cm^2
Therefore, the surface area of each pyramid is 34.125 square centimeters.