Learning pack · IGCSE handout

Trigonometry

What's in this pack: printable worksheet PDF, matching answers PDF (IGCSE / Secure–Stretch practice). Right-angled trigonometry uses $\sin$ , $\cos$ , $\tan$ with opposite, adjacent and hypotenuse. Label the triangle before choosing a ratio.

Resources at the top · full summary · videos with short notes below.

🎒 Resources in this pack

Jump straight to the printable files, or scroll to the summary and videos.

Scaffolded Learning Sheet — attempt the worksheet, then use the Answers for a full written solution.

📝 Open Learning Sheet ✅ Open answers 🎬 More topic videos (6)📖 Full summary

Files: 19_trigonometry_handout.pdf · 19_trigonometry_handout_answers.pdf

Full topic summary

Right-angled trigonometry uses $\sin$ , $\cos$ , $\tan$ with opposite, adjacent and hypotenuse. Label the triangle before choosing a ratio.

Key learning points

SOH-CAH-TOA: pick the ratio that uses the sides you know/need.
To find an angle, use the inverse function.
Check your calculator is in degrees for IGCSE questions.

Worked example 1 — Find a side

Opposite $x$ , hypotenuse $10$ , angle $30^\circ$ . Find $x$ .

Working

x=10\sin30=5

SOH.

Worked example 2 — Find an angle

Adjacent $4$ , hypotenuse $8$ . Find $\theta$ .

Working

\cos\theta=\tfrac{1}{2}\Rightarrow\theta=60^\circ

CAH.

Worked example 3 — Tangent

Opposite $3$ , adjacent $3$ . Find $\theta$ .

Working

\tan\theta=1\Rightarrow\theta=45^\circ

TOA.

🎬 Topic videos

Beautiful Trigonometry - Numberphile
Numberphile · 12 min
Enrichment / curiosity clip for Lower Secondary (Numberphile-style). Use for hooks, clubs, or stretch — not core exam content.
The Cosine Rule (1 of 3: Proof of the Formula)
Eddie Woo · 13 min
Lower Secondary classroom-friendly explainer. Scaffold→stretch friendly; use with mixed-ability groups.
3D Trigonometry Example (1 of 2: Setting up the triangles)
Eddie Woo · 8 min
Lower Secondary classroom-friendly explainer. Scaffold→stretch friendly; use with mixed-ability groups.
Similar Figures
Eddie Woo · 12 min
Lower Secondary classroom-friendly explainer. Scaffold→stretch friendly; use with mixed-ability groups.
Congruent Figures (1 of 2: Introduction)
Eddie Woo · 8 min
Lower Secondary classroom-friendly explainer. Scaffold→stretch friendly; use with mixed-ability groups.
Trigonometry Introduction - Corbettmaths
Corbettmaths · 6 min
Lower Secondary classroom-friendly explainer. Scaffold→stretch friendly; use with mixed-ability groups.

More Lower Secondary packs

Browse the hub Learning Packs & Summary, or open the compact Trigonometry summary.