Author note — to cover (Higher)

Higher only: the cosine rule rearranged to find any angle from three sides, a negative cosine correctly yielding an obtuse angle, with the largest-angle-faces-longest-side check. G22 requires knowing and applying the rule; no right angle may be assumed anywhere in the triangle. (G22)

• Fluency — direct questions on the cosine rule for angles, 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).