The digital SAT provides a reference sheet with some geometry formulas at the start of the Math section. But most formulas are not given to you — you need to have them memorised before test day.
This cheat sheet covers every formula you need, clearly marked as given (on the reference sheet) or memorise (not provided).
Geometry Formulas
These are the most formula-heavy part of the SAT. The reference sheet covers basic shapes — but composite figures, coordinate geometry, and circle theorems are on you.
| Formula | Expression | Status |
|---|---|---|
| Area of a circle | A = πr² | given |
| Circumference of a circle | C = 2πr | given |
| Area of a rectangle | A = lw | given |
| Area of a triangle | A = ½bh | given |
| Pythagorean theorem | a² + b² = c² | given |
| Volume of a rectangular prism | V = lwh | given |
| Volume of a cylinder | V = πr²h | given |
| Volume of a cone | V = ⅓πr²h | given |
| Volume of a sphere | V = 4/3 · πr³ | given |
| Arc length | L = (θ/360) × 2πr | memorise |
| Area of a sector | A = (θ/360) × πr² | memorise |
| Circle equation (standard form) | (x−h)² + (y−k)² = r² | memorise |
| Area of a trapezoid | A = ½(b₁+b₂)h | memorise |
| Special right triangle (30-60-90) | sides: 1, √3, 2 | given |
| Special right triangle (45-45-90) | sides: 1, 1, √2 | given |
Algebra Formulas
None of these are provided on the reference sheet. Every algebra formula must be memorised.
| Formula | Expression | Status |
|---|---|---|
| Slope of a line | m = (y₂−y₁)/(x₂−x₁) | memorise |
| Slope-intercept form | y = mx + b | memorise |
| Point-slope form | y − y₁ = m(x − x₁) | memorise |
| Quadratic formula | x = (−b ± √(b²−4ac)) / 2a | memorise |
| Vertex form of a quadratic | y = a(x−h)² + k | memorise |
| Difference of squares | a²−b² = (a+b)(a−b) | memorise |
| Perfect square trinomial | (a+b)² = a²+2ab+b² | memorise |
| Exponential growth/decay | y = a(1 ± r)^t | memorise |
| Discriminant | b²−4ac (determines number of solutions) | memorise |
Trigonometry Formulas
| Formula | Expression | Status |
|---|---|---|
| SOHCAHTOA | sin = opp/hyp, cos = adj/hyp, tan = opp/adj | memorise |
| Sine rule (complementary angles) | sin(x) = cos(90°−x) | memorise |
| Pythagorean identity | sin²θ + cos²θ = 1 | memorise |
Statistics Formulas
| Formula | Expression | Status |
|---|---|---|
| Mean (average) | mean = sum of values / number of values | memorise |
| Percent change | % change = (new−old)/old × 100 | memorise |
| Probability | P = favourable outcomes / total outcomes | memorise |
| Conditional probability | P(A|B) = P(A and B) / P(B) | memorise |
| Line of best fit (slope) | slope = change in y / change in x | memorise |
How to Actually Memorise These
The most effective way to memorise formulas is not to read them repeatedly — it's to use them repeatedly. Every time you solve a practice question that uses the quadratic formula, the formula gets reinforced. Passive reading of a cheat sheet is far less effective.
What to do instead
- Write out the formulas you don't know from memory on paper each morning — 5 minutes
- Solve at least 5 practice questions per formula until it's automatic
- For geometry formulas, sketch a diagram alongside the formula — visual anchors help
- For the quadratic formula, say it aloud while writing it until it's muscle memory
Put these formulas to work
Practice SAT Math questions that use every formula on this page — with full explanations.