http://www.ck12.org Chapter 1. Basics of Geometry
Solution:It does not matter the placement ofAorBalong the line nor the direction that
−→
CDpoints.Example 8:Describe the picture below using all the geometric terms you have learned.
Solution:
←→
ABandDare coplanar in PlaneP, while←→
BCand←→
ACintersect at pointCwhich is non-coplanar.Know What? RevisitedIf you take the triangles and move them so that the point that met at the center of the square
was on the outside, you would get the figure at the right. However, you could also argue that this is not a shape
because it has a square hole in the center of it. Another shape that can be made from the four triangles is a rectangle.
Part of geometry is justifying and explaining reasoning. You could reason that both of these answers are acceptable.
Review Questions
For questions 1-5, draw and label an image to fit the descriptions.
1.−→
CDintersectingABand PlanePcontainingABbut not−→
CD.
- Three collinear pointsA,B,andCsuch thatBis also collinear with pointsDandE.
−→
XY,
−→
X Z,and−−→
XWsuch that−→
XYand−→
X Zare coplanar, but−−→
XWis not.- Two intersecting planes,PandQ, withGHwhereGis in planePandHis in planeQ.
- Four non-collinear points,I,J,K,andL, with line segments connecting all points to each other.
- Name this line in five ways.