A triangular pyramid has a base shaped like an equilateral triangle. The legs of the equilateral triangle are all 4 centimeters long, and the height of the equilateral triangle is 3.5 centimeters. The pyramid's slant height is 8 centimeters. What is its surface area?

The surface area is 55 cm².

Step-by-step explanation:

The formula to compute the surface area of the triangular pyramid is:

Here h is the slant height.

Compute the Base perimeter as follows:

Perimeter of the equilateral triangle = 3 × side

                                                            = 3 × 4

                                                            = 12 cm

Compute the Base area as follows:

Area of the equilateral triangle = 0.50 × side × height

                                                    = 0.50 × 4 × 3.50

                                                    = 7 cm²

Compute the surface area as follows:

Thus, the surface area is 55 cm².