SAT SUBJECT TEST MATH LEVEL 1

SOLID AND COORDINATE GEOMETRY

CHAPTER 12 Solid Geometry

SPHERES

A sphere is the set of all points in space that are a fixed distance, r, from a given point, OO is called the center of the sphere, and r is the radius.

The two formulas about spheres that you might need to use on the Math 1 test are those for volume and surface area. These two formulas, which are given to you in the “Reference Information” box, constitute the next KEY FACT.

Key Fact K8

• The formula for the volume of a sphere of radius r is .

• The formula for the surface area of a sphere of radius r is A = 4πr2.

Remember

The formulas in KEY FACT K8 are listed in the Reference Information box on the first page of every Math 1 test.

EXAMPLE 7: What is the radius of a sphere whose surface area is equal to the surface area of a cube whose edges are 1?

By KEY FACT K2, the surface area of the cube is 6e= 6(1)= 6. Then by KEY FACT K8,