Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 3 - No. 38)
In the context of the cosine rule, what is the formula for finding the angle A in a triangle with sides a, b, and c?
cos A = (b² + c² - a²) / (2bc)
cos A = (a² + b² - c²) / (2ab)
cos A = (b² - c² - a²) / (2bc)
cos A = (a² - b² - c²) / (2bc)
คำอธิบาย
The formula is cos A = (b² + c² - a²) / (2bc)