ACT Math Formulas

What is the distance formula?

• d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}

• d = \frac{y_2 - y_1}{x_2 - x_1}

• d = (x_2 - x_1) + (y_2 - y_1)

• d = \sqrt{(x_2 + x_1)^2 + (y_2 + y_1)^2}

State the Triangle Exterior Angle Theorem.

• The measure of an exterior angle is equal to the sum of the measures of the two opposite interior angles: @@m\angle 1 + m\angle 2 = m\angle 4@@.

• The measure of an exterior angle is equal to the difference of the measures of the two opposite interior angles.

• The sum of the measures of all angles in a triangle is equal to 180 degrees.

• The measure of an exterior angle is equal to the sum of all three interior angles.

What is the formula for the area of a rectangle?

• @@A = length imes width@@

• @@A = 2(length + width)@@

• @@A = length + width@@

• @@A = length imes height@@

What is the formula for the area of a circle?

• A = πr^2

• A = 2πr

• A = πd^2

• A = r^2 + h^2

What is the formula for the number of diagonals of a polygon with n sides?

• @@rac{n(n-3)}{2}@@

• @@rac{n(n-2)}{2}@@

• @@n(n-1)@@

• @@rac{n(n-4)}{2}@@

What is the formula for the area of a triangle?

• @@A = rac{1}{2} imes base imes height@@

• @@A = base imes height@@

• @@A = rac{1}{3} imes base imes height@@

• @@A = base + height@@

State the Triangle Angle-Sum Theorem.

• The sum of the interior angles of a triangle is 90 degrees: @@m\angle 1 + m\angle 2 + m\angle 3 = 90@@.

• The sum of the interior angles of a triangle is 180 degrees: @@m\angle 1 + m\angle 2 + m\angle 3 = 180@@.

• The sum of the interior angles of a triangle is 360 degrees: @@m\angle 1 + m\angle 2 + m\angle 3 = 360@@.

• The sum of the interior angles of a triangle is 270 degrees: @@m\angle 1 + m\angle 2 + m\angle 3 = 270@@.

What is the formula for the area of a parallelogram?

• @@A = base \times height@@

• @@A = \frac{1}{2} \times base \times height@@

• @@A = length \times width@@

• @@A = base + height@@

What is the formula for the volume of a cylinder?

• @@V = \\pi r^2 h@@

• @@V = 2 \\pi r h@@

• @@V = \\pi r^2 + h@@

• @@V = \\frac{1}{3} \\pi r^2 h@@

What is the formula for the area of a trapezoid?

• @@A = rac{1}{2} (b_1 + b_2) h@@

• @@A = b imes h@@

• @@A = rac{1}{2} (b_1 - b_2) h@@

• @@A = b_1 + b_2 + h@@