1. POINTS IN 3 DIMENSIONS 2D X Y O The xy-plane is used to plot points in 2D. We look down on this from above.

2. 3D X Y Z X-axisleft to right. Y-axisfront to back. Z-axistop to bottom. NB: (a) All 3 axes are perpendicular to each other. (b)(i) X-axis is perpendicular to yz-plane. (ii) Y-axis is perpendicular to xz-plane. (iii) Z-axis is perpendicular to xy-plane.

3. ExSuppose we have a cuboid measuring 4 X 3 X 6 fitted against the axes as shown. X Y Z 4 3 6 O O is (0,0,0) A A is (4,0,0) B B is (4,3,0) C C is (0,3,0) D D is (0,3,6) E E is (4,3,6) F F is (4,0,6) G G is (0,0,6) GB = ( ) 4 3 -6 By inspection GB = b – g = ( ) - ( ) 4 3 0 0 0 6 = ( ) 4 3 -6 Using rule from 2D.

4. NB: On X-axisy = 0 and z = 0.Points O & A. On Y-axisx = 0 and z = 0.Points O & C. On Z-axisx = 0 and y = 0.Points O & G. In xy-planez = 0.Points O, A, B & C. In xz-planey = 0.Points O, A, F & G. In yz-planex = 0.Points O, C, D & G.