To answer the given question, substitute the values given to the equation,
S = π x sqrt(r² + h²)
155 m = π x sqrt (r² + (21 m)²))
r = 44.65 m
Therefore, the radius of the cone is approximately 44.65 m.
The formula for the circumference is 2πr.
The diameter d is given, which is 2 times the radius r (d = 2r)
So you have to calculate π d = 3.142×1.8 ≈ 5.7