To find the surface area of the rectangular pyramid, we need to find the area of each face and then sum them up.
1. The area of the base:
Area = length x width
Area = 8 mm x 10 mm
Area = 80 mm²
2. The area of the four triangular faces:
a) The area of the face with a height of 12 mm:
Area = 1/2 x base x height = 1/2 x 8 mm x 12 mm = 48 mm²
b) The area of the face with a height of 15 mm:
Area = 1/2 x base x height = 1/2 x 10 mm x 15 mm = 75 mm²
3. Add up all the areas:
Surface Area = Base area + 4 x Triangular face area
Surface Area = 80 mm² + 4(48 mm² + 75 mm²)
Surface Area = 80 mm² + 4(123 mm²)
Surface Area = 80 mm² + 492 mm²
Surface Area = 572 mm²
Therefore, the surface area of the rectangular pyramid is 572 square millimeters.