What Calculator Functions Do You Need to Know for the ACT?
Practice Mathematics Test 2 for the ACT — 60 Questions
Six Important Algebra Terms You Must Know for the ACT

Plane Geometry Formulas You Must Know for the ACT

Some of the questions on the ACT Math test deal with plane geometry. Plane geometry is chock-full of useful formulas. If you can’t commit all these formulas to memory and need to prioritize them, memorize everything up to the circumference of a circle. These are the must-know formulas for geometry. Then, if you have time, work your way forward from there.

  • Interior angles of a polygon (the total of all angles inside the polygon):

    Total measure of the interior angles = 180(Number of angles – 2)

  • Area of a triangle:

    image0.png
  • Pythagorean theorem (where a and b are the legs, and c is the hypotenuse):

    a2 + b2 = c2

  • Area and perimeter of a square of side s:

    A = s2

    P = 4s

  • Area and perimeter of a rectangle of sides l and w:

    A = lw

    P = 2l + 2w

  • Area of a parallelogram:

    A = bh

  • Area of a trapezoid:

    image1.png
  • Diameter, area, and circumference of a circle:

    image2.png
  • Arc length of a circle:

    image3.png
  • Volume and surface area of a cube:

    V = s3

    A = 6s2

  • Volume and surface area of a box:

    V = lwh

    A = 2lw + 2lh + 2wh

  • Volume and surface area of a sphere:

    image4.png
  • Volume of a right prism:

    V = Abh

  • Volume of a pyramid:

    image5.png
  • Volume of a cylinder:

    image6.png
  • Volume of a cone:

    image7.png
  • Add a Comment
  • Print
  • Share
blog comments powered by Disqus
ACT Strategy for Multiplying a Matrix by a Real Number
Solving Direct Proportionality Problems on the ACT
ACT Strategy for Multiplying a Horizontal Matrix by a Vertical Matrix
ACT Strategies for Solving Ratios and Proportions
Practice Mathematics Test 1 for the ACT — 60 Questions
Advertisement

Inside Dummies.com