WARM UP 01/09/17 Go over the words and write the Definition of each: Point postulate line plane collinear coplanar segment endpoint ray opposite rays

Review and go over Quiz items: Use the diagram at the right. 1. Name the points on plane S. ANSWER F, K, and Q 2. Name two lines. ANSWER a and b 3. Name the plane that contains point D. ANSWER plane P or plane DFQ

Use the diagram at the right. 4. Name three collinear points. ANSWER F, Q, and W 5. Decide whether the following statement is true or false. Points K, F, and D are coplanar. ANSWER true

ESSENTIAL Question -How do you Identify & Sketch Intersections?

VOCABULARY In geometry, figures intersect if they have any points in common. The intersection of two or more figures is the point or points that the figures have in common.

Intersection of Two Lines POSTULATE Postulate: Intersection of Two Lines If two lines intersect, then their intersection is a point.

Use the diagram at the right. Example 1 Name Intersections of Lines Use the diagram at the right. c. Name the intersection of AC and DF. a. Name the intersection of AC and BE. b. Name the intersection of BE and DF. SOLUTION a. point B. b. point E. c. AC and DF do not appear to intersect. 9

Intersection of Two Planes POSTULATE Intersection of Two Planes If two planes intersect, then their intersection is a line.

In the diagram, planes R, S, & T are intersecting. Example 2 Name Intersections of Planes In the diagram, planes R, S, & T are intersecting. b. Name the intersection of planes R and T. a. Name the intersection of planes S and R. c. Name the intersection of planes T and S. SOLUTION a. at line k. b. Planes R and T do not intersect. c. at line l. 12

Sketch a plane. Then sketch each of the following. Example 3 Sketch Intersections of Lines and Planes Sketch a plane. Then sketch each of the following. a. a line that is in the plane b. a line that does not intersect the plane c. a line that intersects the plane at a point SOLUTION a. Draw the plane. Then draw a line in the plane. 13

Draw the plane. Then draw a line above or below the plane. Example 3 Sketch Intersections of Lines and Planes b. Draw the plane. Then draw a line above or below the plane. c. Draw the plane. Then draw a line that intersects the plane. 14

Homework