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# CA Geometry: Compass construction

56-60, compass construction, coordinates. Created by Sal Khan.

## Want to join the conversation?

• at he said he multiplied both sides of the equation by AB. how did he do that?
• You can do what you want to an equation as long as you do the same thing to both sides. He started with slopeBC = -1/slopeAB, and multiplied both sides by slopeAB. On the left we get (slopeAB)(slopeBC) and on the right we get (-1 * slopeAB)/slopeAB. The slopeABs cancel to leave -1. The equation is thus changed to (slopeAB)(slopeBC) = -1
• how do you construct a hexagon
(1 vote)
• And if you are only allowed to use a compass and a straightedge, then you should make six equilateral triangles.
(1 vote)
• What does Compass Construction mean in geometry?
And also I still don't get how to construct a line parallel to the given line
(1 vote)
• Construction is the drawing of geometric shapes accurately and with the help of mathematical instruments like the compass, ruler etc.
Constructing a line parallel to a given line is perfectly easy. Here's how-
1. Suppose the given line is line m.
2.Draw a perpendicular n to line m at say, point A.
3.Then, draw a perpendicular p to line n.
4.You will see that line p is parallel to line m.
• Hello, I'm just wondering, on the skill, "Compass Constructions" , how exact does the line (straightedge) need to be?
(1 vote)
• If there is a 30' opening of a triangle, how do I figure the lengths of the 2 equal sides that connect at the joining angle?
(1 vote)
• what percent right do you need to pass the test
(1 vote)
• I am not sure how this works.
(1 vote)
• Maybe try reading an article, then watching it again. If this does not work, try reading an explanation in a textbook or asking your teacher.
(1 vote)
• Can you make a perpendicular lines from parallel constructions?
(1 vote)
• What grade would this be?
(1 vote)
• I think there's a mistake. On the very first question, number 56, the answer should be A, because "Scott" marked off four arcs using the endpoints as the pivots. If you connected the resulting x's, he would have a perpendicular line.
(1 vote)