Which of the groups of Exercise 1 are abelian?
Lecture 3: Example: Find the point at which the line x=t, y=2-t, z=1+3t intersects the plane x+y+z=3. Solution: plug in x=t, y=2-t and z=1+3t into the plane equation x+y+z=3. t+(2-t)+(1+3t)=3 3t+3=3 3t=0 t=0 So the point is (x, y, z) = (0, 2, 1) Figure 1 3-dimentional triangle Definition: Two planes are called parallel id their normal vectors are parallel. (Non-pa