Circles summary

Key learning points

• Radius vs diameter: $d=2r$.
• Arc length and sector area are fractions of the full circle: $\frac{\theta}{360}$.
• Exact answers often keep $\pi$; decimal answers need the degree of accuracy stated.

Worked example 1 — Circumference

Radius $7$. Circumference in terms of $\pi$?

Working

$C=2\pi r$.

Worked example 2 — Area

Radius $7$. Area in terms of $\pi$?

Working

Square the radius first.

Worked example 3 — Arc length

Radius $6$, angle $60^\circ$. Arc length in terms of $\pi$?

Working

Fraction of the circumference.

Scaffolded Learning Sheet and answers (PDFs)

This page is a short, searchable overview for revision and search engines. Use the Scaffolded Learning Sheet first, then the Answers PDF for a full written solution. The printable PDFs remain the main classroom resource.