Geometry: Perimeter, Arc Length, and Area

A set of vocabulary flashcards covering basic geometry concepts including perimeter, circle properties like arc lengths and sectors, and area formulas for polygons.

Perimeter

The sum of all sides of a geometric figure.

Length of an Arc

$\frac{\theta}{360} \times 2 \pi r$, where $\theta$ is the angle subtended at the center of the circle.

Circumference of a Semicircle (Arc Only)

$\pi r$, derived from $\frac{180}{360} \times 2 \pi r$.

Perimeter of a Semicircle Figure

The sum of the arc length ($\pi r$) and the diameter ($d$ or $2r$).

Major Sector

The larger region of a circle bounded by two radii and the longer arc.

Minor Sector

The smaller region of a circle bounded by two radii and the shorter arc.

Perimeter of a Sector

$2r + \text{length of the arc}$.

Pythagorean Theorem

$AC^2 = AB^2 + BC^2$, used to find a missing side length for perimeter calculations in right-angled triangles.

Ratio of Perimeters of Two Circles

The ratio of the perimeters of two circles is equal to the ratio of their radii ($\frac{P_1}{P_2} = \frac{r_1}{r_2}$).

Area of a Rectangle

$l \times b$, where $l$ is the length and $b$ is the breadth.

Perimeter of a Rectangle

$2(l + b)$, where $l$ is the length and $b$ is the breadth.

Area of a Parallelogram

$\text{base} \times \text{height}$.