If a and b equals 5 c equals 6 and d equals 4 whats the area of this triangle?

Assuming the sides of the triangle a=5, b=5 and c=6, the semiperimeter s=(5+5+6)/2=8. Height d=3 is not necessary if you use Heron´s formula for the area (A): A = [s(s-a)(s-b)(s-c)]1/2 = [8(8-5)(8-5)(8-6)]1/2 = [144]1/2 = 12