If the sides of a triangle are in the ratio  then greatest angle is

The correct answer is:

In this question we are given the ratio of sides of a triangle 
Let the sides of the triangle be  where K is a constant.
It can be easily seen that  is the largest side. We know that the side opposite to greatest angle is always greatest. So,  will be the greatest angle.
By using Cosine Rule

By substituting the value of a, b, c in the above expression we get,

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