Respuesta :

Diameter = 2r
so 
d = 10.4 * 2
d = 20.8

Circumference = 2 pi r
C = 2 (3.14) (10.4)
C = 65.312

Area = pi r^2
A = (3.14) (10.4)^2 
A = 339.6224
≈ 340

Just get the formula, then plug in the given

Hope this helps :)