1 / 15

Intro to Geometric Constructions

Intro to Geometric Constructions. EQ: How do you use a compass for constructions?. The Super Seven!. Copying a line segment Copying an angle Bisect a line segment Bisect an angle Perpendicular Lines- On line Perpendicular Lines- Off line Parallel Lines. Terminology.

pippa
Download Presentation

Intro to Geometric Constructions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Intro to Geometric Constructions EQ: How do you use a compass for constructions?

  2. The Super Seven! • Copying a line segment • Copying an angle • Bisect a line segment • Bisect an angle • Perpendicular Lines- On line • Perpendicular Lines- Off line • Parallel Lines

  3. Terminology Bisect: to cut or divide into two equal parts Compass: an instrument used to draw circles and to mark equal lengths A’: a copy of point A (pronounced A prime) arc: part of a circle

  4. Copy a Segment • 1. Draw a second line segment (longer than the original). Label the left end point A’. • Put the compass on point A. Move the marker (pencil) until the circle is on top of point B.Do not move the compass setting. • Pick up compass and put it on A’. Swing an arc that intersects the line segment. This point is your B’. A B

  5. Copying An Angle • Draw a ray and label it Y’ and Z’ • Put the compass on point Y and swing (draw) an arc through XYZ. Do not move the compass setting. • Label the points where the arc intersects A and B. • With the compass at the same setting, put the compass on Y’ and draw a large arc through ray Y’Z”. Label the intersection B’. • Go back to XYZ and measure the distance from A to B. • Leave the compass on that setting. • Put the compass on point B’ and make a tiny arc above Ray Y’Z’. This will be A’. • Draw the ray from Y’ through the arc at A’. X Y Z

  6. Constructing Bisectors! EQ: What types of triangles are formed when bisecting angles?

  7. Bisect a Line Segment 1. Put the compass on point A. Open the compass to just a little more than half the length of the line. Draw (swing) a large arc. DO NOT MOVE THE COMPASS SETTING. 2. Put the compass on point B and draw another large arc. 3. Put the straight edge straight through the point where the arcs intersect. Draw the straight line up and down through the segment. Label the point C on the line segment. This is the middle point of the line segment. A B

  8. Bisect an Angle • Put compass on B. • Make an arc through approx. the middle of the angle. • Label the intersections D and E. • Put compass on point D and put a tiny arc in the middle of the ray even with the arrows. Do not move the compass setting. • Put compass on point E and make another tiny arc in the middle of the ray and even with the arrows. • The two tiny arcs form the intersection which BISECTS the angle. • Draw a straight line from point B through the two tiny arcs. Label this point on the tiny arcs F. A B C

  9. Perpendicular and Parallel Lines EQ: What types of triangles are formed from perpendicular lines?

  10. Perpendicular Line With A Point on the Line

  11. Perpendicular Line With a Point NOT on the Line bigger

  12. The Last Constructions! EQ: How can I use my knowledge of constructions to make special angles?

  13. Parallel Lines

  14. Challenge! See if you can figure out how to make the following constructions… • An equilateral triangle • A 45 degree angle • A 60 degree angle • A 30 degree angle Constructions Site

  15. Homework! Pick 1 of the constructions we did today. Write a set of instructions for them, in kid-friendly terms. Include step-by-step pictures. Parallel lines Equilateral triangle 30 degree angle 45 degree angle 60 degree angle

More Related