# Parametric Equations: Summary

It’s possible to represent curves with pairs of parametric equations. At A Level, you need to understand and work with many kinds of parametric equations.

### More videos on Parametric Equations: Summary:

Parametric Equations: Summary

Parametric Function Tables

The Coordinates Given by Parametric Equations

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Up Learn – A Level Maths (edexcel)

## Coordinate Geometry II

1. Introduction to Parametric Equations
2. What are Parametric Equations?
3. Parametric Function Tables
4. The Coordinates Given by Parametric Equations
5. Sketching the Curves of Parametric Equations
6. Sketching Curves within a Restricted Domain
7. What is a Parameter?
8. Turning Parametric Equations into a Cartesian Equation
9. Taking Shortcuts when finding Cartesian Equations
10. Turning Cartesian Equations into Parametric Equations
11. Trigonometric Parametric Equations
12. The Problem with Trigonometric Parametric Equations
13. Converting When the Trig Functions are the Same
14. Converting When the Trig Functions are Reciprocals
15. Using the Pythagorean Identity
16. A Faster Way to Use the Pythagorean Identity
17. Using the Other Pythagorean Identities
18. The Secret Power of the Reciprocal Identities Part 1
19. The Secret Power of the Reciprocal Identities Part 2
20. Parametric Equations We Can Convert So Far
21. Multiple Trig Functions in One Parametric Equation
22. Using the Double Angle Identities
23. Using the Compound Angle Identities
24. The Domain and Range of Parametric Equations
25. Finding Unknown Coordinates
26. Finding Points of Intersection in Parametric Form
27. Points of Intersection with Parametric Trig Equations
1. Introduction to 3D Coordinates
2. The z-axis
3. 3D Coordinates
4. Plotting 3D Coordinates
5. Rotating the Euclidean Space
6. Pythagoras in 3D – Part 1
7. Pythagoras in 3D – Part 2
8. Distance from the Origin
9. Distance Between Two Points

Space Lieutenant James Johnson hurtled through fleets of enemy ships, blasting them to smithereens as he raced through the edge of the universe.

[Cheesy, macho, deep space lieutenant voice] “These fools,” barked Johnson.

“They always come straight for me!

Either that, or they…sorta…just zig-zag at me…

I…am…an untouchable…machine”

Kris paused the game he’d been working on.

At any moment, the position of each of his enemy ships was given by a set of x and y coordinates.

[Show axes over the computer screen]

And so far, he’d only programmed two paths for the enemy ships.

First, he’d have ships fall vertically down the screen.

And to do that, every half second, Kris made the y coordinates of these ships…

Every half second, Kris made the y coordinates of these ships decrease.

Second, he also made some ships move down in a zig-zag pattern.

To do that, every half second, Kris also changed the…

Kris also changed the x coordinate of some of his ships.

But, his game had become too easy, and Kris needed some enemy ships to start following a more challenging path…

So, he decided to have an all-new fleet of ships trace out a deadly circle – leaving explosive mines for

Space Lieutenant James Johnson to dodge…or be annihilated by…

Now, Kris already knew that the equation of a circle is…

Kris already knew that this is the equation of a circle.

And he knew that he wanted the circle’s radius to be 100 units on screen.

So first, he tried to figure out how he needed to change each ship’s x coordinate every half second.[Press Here]

To do that, he rearranged his equation and got…this [x=±1002-y2]

However… he didn’t know what value to replace y with…

Not deterred, Kris rearranged the equation again to get the value of y

But this time, he got…

This time, Kris found that y was equal to this [y=±1002-x2]

So, Kris needed to know the x value to update the y value…

And the y value to update the x value…

But, he didn’t know either of them!

With his straight and zig-zag paths, this wasn’t a problem: he could add something to his x and y coordinates separately.

But now, the circle equation defined x and y in terms of each other…

If Kris was ever going to fix his game, and give Space Lieutenant James Johnson a real challenge, he’d need to separate out x and y in the circle equation.

And, if he was going to do that, cartesian equations would no longer be enough.

Instead, he would have to learn about a whole new system for building equations…

He would have to understand…parametric equations…