Find the surface area of the equilateral triangular pyramid.
a) 97.5 in2 b) 225 in2 c) 322.5 in2 d) 645 in2

 The area of the base is given by:
 A1 = (1/2) * (15) * (13)
 A1 = 97.5
 The area of the lateral faces is given by:
 A2 = (1/2) * (15) * (10)
 A2 = 75
 Then, the total surface area is:
 A = A1 + 3A2
 Substituting values:
 A = 97.5 + 3 * (75)
 A = 322.5
 
 The surface area of the equilateral triangular pyramid is:
 C) 322.5 in2