Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 3 - No. 26)
Which of the following are true about the Cosine Rule?
a² = b² + c² - 2bc cos A
The rule is used to find the length of a side in a triangle.
The rule is only useful when there's at least one right angle
It involves the cosine of one of the angles.
คำอธิบาย
Correct statements include the formula, the use of the rule to find sides and involves the cosine of the angle