Question

complete each statement with always, sometimes, or never.

1. any three points ____ determine a plane.
2. two planes ____ intersect in a line.
3. a line ____ has endpoints.
4. a segment ____ has endpoints.

Explanation:

Question 15:

Step1: Recall plane - point relationship

Three non - collinear points always determine a plane, but if three points are collinear, they lie on a line and there are infinitely many planes that can contain that line. So any three points sometimes determine a plane.

Question 16:

Step1: Recall plane - plane intersection

Two parallel planes never intersect. Two non - parallel planes intersect in a line. So two planes sometimes intersect in a line.

Question 17:

Step1: Recall the definition of a line

A line is defined as a straight one - dimensional figure that extends infinitely in both directions. By definition, a line never has endpoints (endpoints are a characteristic of line segments or rays).

Question 18:

Answer:

1. sometimes
2. sometimes
3. never
4. always