
Q1 A point is on the xaxis. What are its ycoordinates and zcoordinates? Ans: If a point is on the xaxis, then its ycoordinates and zcoordinates are zero.
Q2 A point is in the XZplane. What can you say about its ycoordinate? Ans: If a point is in the XZ plane, then its ycoordinate is zero.
Q3 Name the octants in which the following points lie: (1, 2, 3), (4, –2, 3), (4, –2, –5), (4, 2, –5), (–4, 2, –5), (–4, 2, 5), (–3, –1, 6), (2, –4, –7) Ans: The xcoordinate, ycoordinate, and zcoordinate of point (1, 2, 3) are all positive. Therefore, this point lies in octant I.
The xcoordinate, ycoordinate, and zcoordinate of point (4, –2, 3) are positive, negative, and positive respectively. Therefore, this point lies in octant IV.
The xcoordinate, ycoordinate, and zcoordinate of point (4, –2, –5) are positive, negative, and negative respectively. Therefore, this point lies in octant VIII.
The xcoordinate, ycoordinate, and zcoordinate of point (4, 2, –5) are positive, positive, and negative respectively. Therefore, this point lies in octant V.
The xcoordinate, ycoordinate, and zcoordinate of point (–4, 2, –5) are negative, positive, and negative respectively. Therefore, this point lies in octant VI.
The xcoordinate, ycoordinate, and zcoordinate of point (–4, 2, 5) are negative, positive, and positive respectively. Therefore, this point lies in octant II.
The xcoordinate, ycoordinate, and zcoordinate of point (–3, –1, 6) are negative, negative, and positive respectively. Therefore, this point lies in octant III.
The xcoordinate, ycoordinate, and zcoordinate of point (2, –4, –7) are positive, negative, and negative respectively. Therefore, this point lies in octant VIII.