ACT Geometry Starter Pack

A complete set of VOCABULARY flashcards covering ACT geometry formulas, conceptual reminders, and example calculations based on the provided starter pack.

Rectangle area formula

$$A = l \times w$$

Rectangle perimeter formula

$$P = 2l + 2w$$

Triangle area formula

$$A = \frac{1}{2} \times b \times h$$

Circle area formula

$$A = \pi r^2$$

Circle circumference formula

$$C = 2\pi r$$

Pythagorean theorem

$$a^2 + b^2 = c^2$$

Midpoint formula

$\left(\frac{x_1+x_2}{2}, \frac{y_1+y_2}{2}\right)$.

Distance formula

$$\sqrt{(x_2-x_1)^2 + (y_2-y_1)^2}$$

Slope formula

$$\frac{y_2-y_1}{x_2-x_1}$$

Area (conceptual definition)

Measurement of the inside of a shape.

Perimeter/circumference (conceptual definition)

Measurement around a shape.

Diameter relationship to radius

The diameter is twice the radius.

Radius relationship to diameter

The radius is half the diameter.

Hypotenuse definition

The longest side of a right triangle, represented as $c$ in the Pythagorean theorem.

Triangle area calculation procedure

Multiply base and height, then cut it in half.

Midpoint calculation procedure

Average the $x$-values and average the $y$-values.

Radius for a circle with diameter $10$

$$5$$

Circumference of a circle with radius $6$

$$12\pi$$

Area of a circle with radius $6$

$$36\pi$$

Area of a triangle with base $12$ and height $7$

$$42$$

Area of a rectangle with length $9$ and width $4$

$$36$$

Perimeter of a rectangle with length $9$ and width $4$

$$26$$

Midpoint of $\left(2, 6\right)$ and $\left(10, 14\right)$

$$\left(6, 10\right)$$

Distance between $\left(1, 2\right)$ and $\left(1, 9\right)$

$$7$$

Perimeter of a rectangle with length $11$ and width $5$

$$32$$

Area of a triangle with base $14$ and height $9$

$$63$$

Circumference of a circle with radius $4$

$$8\pi$$

Area of a circle with diameter $12$

$$36\pi$$

Hypotenuse of a right triangle with legs $8$ and $15$

$$17$$

Area of a rectangle with width $7$ and length $4$ feet longer than width

$$77$$

Height of a triangle with area $30$ and base $12$

$$5$$

Radius of a circle with circumference $18\pi$

$$9$$