Author note — to cover

Define sin, cos and tan as side ratios — formulas G20 says must be known — labelling hypotenuse, opposite and adjacent relative to the chosen angle, in any orientation. Right-angled triangles only: general triangles are Higher, in the sine and cosine rules group. Both tiers. (G20)

• Fluency — direct questions on the trigonometric ratios, 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).