Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 6 - No. 28)
If you are given a triangle with sides a, b, and c, and you know the value of angle C, which rule would you use to find the length of side c?
Sine Rule
Cosine Rule
Tangent Rule
Pythagorean Theorem
Explication
The Cosine Rule is the correct method in this scenario.