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Corbett MathsTrigonometry — SOH CAH TOA
Corbett MathsSine rule and cosine rule
GCSE Maths TutorThe Cosine Rule | Grade 7 Maths Revision | GCSE Maths Tutor
Key facts & methods
Right-angled triangle trigonometry — fill in the table
| Rule | Formula / meaning |
|---|
| Pythagoras | |
| sin θ | |
| cos θ | |
| tan θ | |
| Finding an angle | |
| Elevation / depression | |
| 3D Pythagoras | |
Sine rule and cosine rule — fill in the table
| Rule | Formula / use |
|---|
| Sine rule | |
| Cosine rule | |
| Cosine rule (find angle) | |
| Area of any triangle | |
Exam questions — 5 questions · 14 marks · Edexcel 4MA1 style
⚡ Show ALL working — the AI awards method marks just like a real examiner. Partial credit for correct working even if the final answer is wrong.
3 marksPythagoras and trig4MA1 style 🔢 Calculator
A right-angled triangle has legs of length 7 cm and 9 cm. (a) Find the hypotenuse to 2 d.p. (b) Find the smallest angle in the triangle. (3 marks)
Hint: (a) Pythagoras: c² = a²+b². (b) Smallest angle is opposite the shortest side (7cm). Use sin θ = opp/hyp or tan θ = opp/adj.
+30 XP
3 marksSine rule4MA1 style 🔢 Calculator
In triangle ABC, angle A = 34°, angle B = 72°, and side b = 14.5 cm. Find side a. Give your answer to 3 significant figures. (3 marks)
Hint: Find angle C first (angles sum to 180°). Apply sine rule: a/sin A = b/sin B. Cross-multiply to find a.
+30 XP
3 marksCosine rule — find angle4MA1 style 🔢 Calculator
A triangle has sides 8 cm, 11 cm and 14 cm. Find the largest angle. Give your answer to 1 decimal place. (3 marks)
Hint: Largest angle is opposite the longest side. Use rearranged cosine rule: cos A = (b²+c²−a²)/(2bc). A negative value means an obtuse angle.
+30 XP
3 marksArea of triangle4MA1 style 🔢 Calculator
Two sides of a triangle are 7 cm and 10 cm. The angle between them is 63°. Calculate the area of the triangle. (3 marks)
Hint: Area = ½ab sin C. The angle C must be the angle BETWEEN the two given sides (the included angle).
+30 XP
1 mark3D Pythagoras4MA1 style
A cuboid has dimensions 3 cm × 4 cm × 12 cm. What is the length of the longest diagonal?
A 13 cm
B 19 cm
C 15 cm
D 7 cm
Quick recall flashcards
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