ACT Math Formula Sheet — Definition, Formula & Examples
An ACT Math formula sheet is a organized reference of the key formulas you need to memorize for the ACT Math section. Unlike the SAT, the ACT does not provide any formulas on test day, so you must know them by heart.
A compilation of algebraic, geometric, and trigonometric identities and relations — including area and volume formulas, the quadratic formula, slope-intercept form, SOHCAHTOA ratios, and probability rules — that appear frequently on the 60-question ACT Mathematics test. No formula reference is supplied during the exam.
How It Works
The ACT Math section covers six content areas: pre-algebra, elementary algebra, intermediate algebra, coordinate geometry, plane geometry, and trigonometry. For each area, a small set of formulas accounts for the majority of questions. Memorize them in groups: start with area and volume formulas for geometry, then linear and quadratic equations for algebra, then trig ratios and identities. Practice applying each formula with timed drills so recall becomes automatic under test conditions. Focus especially on formulas you cannot derive quickly, such as the quadratic formula or the law of cosines.
Worked Example
Problem: A circle has a radius of 5. A sector of that circle has a central angle of 72°. Find the area of the sector.
Recall the formula: Sector area equals the fraction of the full circle times the circle's area.
Substitute values: Plug in the central angle 72° and radius 5.
Simplify: Multiply to get the exact area.
Answer: The sector area is or approximately 15.71 square units.
Why It Matters
Every ACT Math point can affect your composite score and scholarship eligibility. Because no reference sheet is provided, students who have formulas memorized save time and avoid careless errors. Knowing roughly 15–20 core formulas covers the vast majority of the 60 questions on the test.
Common Mistakes
Mistake: Assuming the ACT provides formulas like the SAT does
Correction: The ACT gives zero formulas. You must memorize area, volume, slope, quadratic, and trig formulas before test day. Build a study schedule that drills a few formulas each week.