Normally when asked about the surface area, the lateral surface area is the one being referred to but let me just consider both the lateral surface area and the total surfX:VV
For the lateral surface area, you'll have the formula:
A = π r l
where A is the area
         r is the radius 
         l is the slant height
A = π (3cm)(7cm)
A = 21 π cm²
A = 65.97 cm²

For the total surface area, you'll have:
A = π r l + π r²
A = π(3cm)(7cm) + π(3cm)²
A = 30 π cm²
A = 94.25 cm²