Circumference and Area of Circles Flashcards

Grade 7 · Math · Flashcards

Vocabulary and formulas for finding circumference and area of circles.

Flashcards

Radius (r): The distance from the center of a circle to any point on its edge
Diameter (d): The distance across a circle through its center; d = 2r
Pi (π): The ratio of circumference to diameter for any circle; approximately 3.14 or 22/7
Circumference formula (using diameter): C = πd
Circumference formula (using radius): C = 2πr
Area formula: A = πr² — square the radius, then multiply by pi
Finding radius from diameter: r = d ÷ 2
Units for circumference: Linear units (cm, m, ft, in) — it is a distance
Units for area: Square units (cm², m², ft²) — it is a 2D measurement
Irrational number: A number whose decimal expansion never ends or repeats; pi is irrational