Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 4 - No. 12)
A triangle has sides of length 4cm, 5cm, and 7cm. What angle would be calculated using the formula cos A = (b² + c² - a²) / (2bc)?
The angle opposite the side of length 4 cm.
The angle opposite the side of length 5 cm.
The angle opposite the side of length 7 cm.
Cannot determine the angle.
คำอธิบาย
In cosine rule, the angle to be calculated is always opposite to side a.