Many students are blown away by the fact that every SAT Math Section has a geometry cheat sheet at the very beginning (hopefully, they pick up on this before they take the actual test).
Today, I’m going to do better than just rehash those formulas. I’m going to tell you which ones you should memorize (since it’ll make you faster on test day) and which ones you can refer back to (since you don’t want to cram more unnecessary information in your head).
Math formulas provided for you on the SAT
1. Circumference and area of a circle
Recall this formula as naturally as you can recall your home address. It’s easy:
Area = πr^2
Circumference = 2πr
And don’t mix the two up!
2. Area of a rectangle
This one should be pretty intuitive. To find the area of a rectangle/square multiply length x width (they are the same in a square). Perimeter, which is not part of the SAT cheat sheet, is found by adding the length and width and multiplying by 2.
3. Area of a triangle
It’s 1/2 of the base x the height. Don’t waste time flipping the pages back and forth. Know this cold.
4. Volume of a box
Don’t memorize this—just refer back to the page if necessary. One thing you don’t get is the surface area of a box. For a cube, things are much easier: volume is s^3, in which s = the side; surface area is 6s^2.
You probably won’t see a problem relating to a cylinder. Anyhow, it’s not that easy to memorize. So it’s great to see it as part of the cheat sheet at the beginning of each section.
6. Pythagorean Theorem
Know this cold. And be fluent and being able to find the missing sides.
7. 30:60:90 triangle
Don’t feel you have to know this cold, though it will make things faster. Just make sure you know what everything stands for when you refer to the diagram.
As a tutor, I always want to make sure my students know this well. But at the end of the day, if you don’t know memorize the formula, you can just use the cheat sheet. Just make sure you know how the sides are connected.
For instance, sometimes you can have a √2 as one of the sides. The relationship between the two equal sides and the hypotenuse is that the hypotenuse will always be √2 times greater.
Formulas not on the SAT’s math cheat sheet
- Volume of a cone: 1/3 πr^3
- Volume of a sphere: 4/3 πr^3
- Average: Total/# of numbers (This is the only non-geometry formula. It’s very important that you know this. I’d recommend memorizing it, or at least understand how it is derived).
- Length of the longest possible line you can draw between two points in a cube: s√3