yr2 chap 8 parametrics

• to find dy/dx when you have x and y in terms of t, use:

  dy/dx = dy/dt divided by dx/dt
• if you have a curve with parametric equations which meets another curve, substitute the x and y values from the parametric equations into the equation of the other curve and solve for t
• a cartesian equation only involves x and y
• to find a cartesian equation from parametric equations, rearrange one of the parametric equations to be in terms of t, substitute that value of t into the other parametric equation