#77 · Trigonometry · Triangles and circles

The sine rule sees the circle

For a triangle with a side $a$ opposite angle $A$ , prove that $\frac{a}{sin A} = 2 R$ , where $R$ is the radius of the triangle's circumscribed circle.

~14 minWritten answer · check your work with LemmaInscribed angle theoremCircumcircle

Stuck? A gentle nudge

Something off?

Workspace

Your working

Check your full solution

Attach photos of your pages (up to 3) or one PDF — or check what you typed above. Lemma reads the work and verifies the reasoning, not just the answer.

Your first check today doesn't need an account.

Your photos and PDFs are read once and not stored — only the transcription is kept.