Q. 4

# 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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