To find the radius of the circular bad, use the Pythagorean thereom.
A^2 + B^2 = C^2
Substitute A^2 with the height, 55, and C^2 with the slant height, 73.
55^2 + B^2 = 73^2
Then simplify
3025 + B^2 = 5329
Subtract 3025 from both sides
B^2 = 2304
Find the square root of both sides
B = 48
The radius of the base of the cone is 48.
If you have any frther questions feel free to ask.
Hope this helps.