McGraw Hill Integrated II, 2012
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McGraw Hill Integrated II, 2012 View details
5. Radical Equations
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Exercise 1 Page 261

Substitute the given value into the formula for the surface area of a sphere.

r=sqrt(Ď€ x)/2Ď€

Practice makes perfect
We are given a formula for the surface area of a sphere. SA=4Ď€ r^2

There is a basketball with a surface area of x square inches.

Sphere
We will find the radius r of this basketball by substituting SA= x into the formula.
SA=4Ď€ r^2
x=4Ď€ r^2
4Ď€ r^2=x
â–Ľ
Solve for r
r^2=x/4Ď€
r=sqrt(x/4Ď€)
r=sqrt(x)/sqrt(4Ď€)
r=sqrt(x)* sqrt(Ď€)/sqrt(4Ď€)* sqrt(Ď€)
r=sqrt(xπ)/sqrt(4π^2)
r=sqrt(xπ)/2π
r=sqrt(Ď€ x)/2Ď€
The radius of the basketball is sqrt(Ď€ x)2Ď€ inches.