Q4 of 87 Page 10

In a ∆ABC, if a = 18, b = 24, c = 30, find cos A, cos B and cos C.

Note: In any ΔABC we define ‘a’ as length of side opposite to ∠A , ‘b’ as length of side opposite to ∠B and ‘c’ as length of side opposite to ∠C .


Key point to solve the problem:


Idea of cosine formula in ΔABC


•


Cos A =


• Cos B =


• Cos C =


As we have a = 18, b = 24 and c = 30


∴ Cos A =


Cos B =


Cos C =


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