Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 7 - No. 38)
In the cosine rule, how do you know which angle to calculate the cos of?
The angle opposite the longest side.
The included angle.
The angle opposite side 'a'.
Any angle.
คำอธิบาย
The angle is opposite to the side length you are trying to calculate.