Author note — to cover

Recover an angle from two known sides with inverse sin, cos and tan, choosing the correct side pair first, answers typically to one decimal place; read the inverse notation as the angle whose sine is, never as a reciprocal. Right-angled triangles only. Both tiers. (G20)

• Fluency — direct questions on finding an angle with trigonometry, limited to this lesson's stated scope (4 questions).
• Application — use the same skill in unfamiliar or contextual questions without introducing a later method (4 questions).
• Check — questions built around the exclusions and likely misconceptions named in the lesson brief (4 questions).