## Thursday, May 28, 2009

### BOB likes to eat icecream [cones]

I feel pretty confident for the test tomorrow, I might not get 100% but I believe I'll do better than what I have been doing so far. I liked this unit because it was pretty straight forward and I had no real trouble understanding any concepts.

I think that for this unit I just need to make sure I know the formulas really REALLY well. Let's review shall we ^__^

A PARABOLA:
The equations:

If the x is squared, the parabola is vertical (either opens up or down) and if the y is squared the parabola opens horizontally (opens left or right). p is the distance from the vertex to the directrix and the focal point. If 4p is a big number, the stretch of the parabola is also big. If the number is smaller than one the parabola will be skinny.

A CIRCLE:
The equation:

r is the radius. In general form, the coefficients of x and y are squared and are the same. That's how you know it's a circle!

AN ELLIPSE:
The equations:

When a (the bigger number) is under x, the ellipse is horizontal. If it's under y then its vertical.
a is the length of the semi major axis. b is the length of the minor axis. Use c^2 = a^2 - b^2 if you have to find the distance between the origin and the focal points. In general form, the coefficients for x and y are different.

A(N) HYPERBOLA:
The equations:

When x is positive the hyperbola is horizontal (opens right and left). When y is positive it is vertical (up and down). a is the length of the semi transverse axis, while b is the length of the semi conjugate axis.

use c^2 = a^2 + b^2 to find c, the distance from the origin to the focal points.

hyperbola graphs have asymptotes! use the slope formula to figure out their equations.

To be alright for the test, all we need to know are the formulas and how to graph them. I'm sure everyone will do fine! ;D

Make sure to eat healthy, drink plenty of water and get some rest so you can be in top shape tomorrow morning!

~Bye bye! :D