Q. 4

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

Answer :

**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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