Parametric equations

What you'll learn

1. 1

   A parametric equation is like a set of instructions that tell a point where to go over time. Imagine a robot that moves along a path — its x-position and y-position are both controlled by a hidden timer called t.

2. 2

   In parametric equations, what does 't' usually stand for?

3. 3

   Drag the slider for t from 0 to 2π and watch the point trace a circle.

4. 4

   Let's find the coordinates when t = π/2 for x = cos(t), y = sin(t).

5. 5

   Now try x = 2cos(t), y = 2sin(t). Slide t to see what happens.

6. 6

   For x = 2cos(t), y = 2sin(t), what is the radius of the circle?

7. 7

   If x = t², y = t, what is y when x = 9?