Question

1. choose the correct answer.

what is the locus of points in a plane that are 3 inches from point a?
a line segment 3 inches long.
a sphere with center a and radius 3 inches.
an angle with sides 3 inches long.
a circle with center a and radius 3 inches.

1. choose the correct answer.

what is the locus of points in three - dimensional space that are 3 inches from point b?
two parallel lines 3 inches apart.
a line segment 3 inches long.
a sphere with center b and radius 3 inches.
a circle with center b and radius 3 inches.

Explanation:

Step1: Recall the definition of locus in a plane

The locus of points in a plane at a fixed distance (radius) from a fixed point (center) is a circle.

Step2: Recall the definition of locus in 3 - D space

The locus of points in three - dimensional space at a fixed distance (radius) from a fixed point (center) is a sphere.

Answer:

1. D. A circle with center A and radius 3 inches.
2. C. A sphere with center B and radius 3 inches.