Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 6 - No. 46)
In a triangle ABC, which is the correct application of the cosine rule when solving for angle A?
a² = b² + c² - 2bc * cosA
cosA = (b² + c² - a²) / (2bc)
cosA = (a² + b² - c²) / (2ab)
A = √(b² + c² - 2bc * cosA)
설명
The cosine rule can be used for find angle.