1. Parametric Equation

2. We express x,y and z, in terms of the parameter t.
This form is known as a parametric equation.

3. Symmetric form
Parametric form

4. Using the coordinates of the point A
Symmetric form
Parametric form

6. Intersection of two lines
Show that the lines L1 and L2 intersect and
find the point of intersection

7. Use simultaneous equation to find t and s

8. we must check that s and t
also satisfy the third equation
The values for t and s satisfy all three equation and
the lines L1 and L2 do intersect.

9. If you use L1 use the parameter t = 2

10. Angle between two lines
The angle between two lines is the same as
the angle between the direction vectors of the line.
The angles can be found as follows
Find a vector a in the direction of L1
Find a vector b in the direction of L2
The angle between a and b is the same
as the angle between L1 and L2

12. Note that this calculation may give the obtuse angle
between the lines. If so, use supplementary angles
to find the acute angle.