Math
posted by Chris .
A spherical tree ornament is to be painted in bright colors. If the ornament has a diameter of 4 cm,
how much paint is needed?

Wouldn't it depend on how well the paint covers area?

The amount of paint you need is the exact same amount of area the ornament has.
The problem tells you that the ornament is a sphere, so the formula for area is
A = &pid^{2}
since we know d=4cm them we have
A = &pi*(4cm)^{2}
A=16cm^{2}
Since A = the amount of paint we found the answer 16cm^{2} 
In contrast to michael's post, the formula for the surface area of a square is actually
A = 4 (pi)* r^2
Since the diameter is 4, the radius = 2, so
A = 4 (pi) * 4 = 16 (pi) = 16 (3.1416) = ?
I hope this helps a little more. Thanks for asking.