Help with ACT prep: Must-know formulas?

Hey everyone! I'm preparing for the ACT, and I was wondering, what are some essential formulas or concepts I should keep in mind while studying? Are there any useful math tips or tricks anyone could share with me?

Hello! As you study for the ACT, here's a list of essential formulas and concepts you should keep in mind for the Math section:

1. Arithmetic and Geometric Sequences

- Arithmetic: an = a1 + (n-1)d

- Geometric: an = a1 r^(n-1)

2. Quadratic formula: x = (-b ± sqrt(b^2 - 4ac)) / 2a

3. Distance formula: √((x2-x1)^2 + (y2-y1)^2)

4. Midpoint formula: ((x1+x2)/2, (y1+y2)/2)

5. Slope-intercept form: y = mx+b

6. Point-slope form: y-y1 = m(x-x1)

7. Pythagorean theorem: a^2 + b^2 = c^2

8. Trigonometry ratios (SOH-CAH-TOA):

- sine = opposite/hypotenuse,

- cosine = adjacent/hypotenuse,

- tangent = opposite/adjacent

9. Area formulas:

- Rectangle: A = lw,

- Triangle: A = (1/2)bh,

- Circle: A = πr^2

10. Volume formulas:

- Rectangular prism: V = lwh,

- Cylinder: V = πr^2h,

- Sphere: V = (4/3)πr^3

11. Circle properties:

- Circumference: C = 2πr,

- Arc length: L = (n°/360°) 2πr

12. Simple and compound interest:

- Simple: A = P(1 + rt)

- Compound: A = P(1 + r/n)^(nt)

For useful math tips or tricks, I recommend:

1. When you're stuck, try plugging in answer choices or numbers you generate yourself to test the options.

2. Familiarize yourself with the calculator you'll use on test day. Knowing how to use the functions efficiently will save time.

3. Along with studying, practice time management on official ACT practice tests. This will help you gauge how much time you can spend per question.

4. For geometry problems, draw a diagram and label the given information.

5. Break down word problems step-by-step and underline essential information.

Best of luck in your ACT prep!