Sine and cosine rule
Apply the sine rule, cosine rule and area = 0.5ab sin C to non-right-angled triangles
What you'll learn
- 1
Imagine a triangle that is not a right angle — like a slice of pizza that's been squashed! 🍕
- 2
What kind of triangle do the sine and cosine rules work for?
- 3
Let's use the sine rule to find a missing side. In triangle ABC, side a = 5 cm, angle A = 30°, angle B = 50°. Find side b.
- 4
In the sine rule, which fraction is correct?
- 5
The cosine rule is like a magic formula for triangles when you know two sides and the angle between them. 🪄
- 6
Find side a in a triangle where b = 7 cm, c = 9 cm, and angle A = 60°.
- 7
What is the cosine rule for side a?
- 8
Which rule would you use to find side x? You know sides y and z, and the angle between them.
Practise Sine and cosine rule with Whizlo
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