Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 1 - No. 38)
A boat, C, is 10km away on a bearing of 090 degrees. Boat, B, is 6km away on a bearing of 150 degrees from the same point. What is needed to calculate the distance between the two boats?
Cosine rule
Pythagoras theorem
Sine rule
tan
Explication
The cosine rule should be used when two sides and an included angle are known.