Regular triangular pyramid has the slant height k=12 cm and lateral area AL = 198 cm2. Find the length of the base edge.

If s represents the edge length of the base, the lateral area is given by

A = (1/2) * (3s) * (k)

We can substitute the given numbers and solve for s.

198 cm² = (1/2) * (3s) * (12 cm)

(198 cm²) / (18 cm) = s

s = 11 cm

The length of a base edge is 11 cm.