Q.

The locus of z which lies in shaded region (excluding the boundaries) is best represented by                  [2005]

1 z:|z+1|>2 and |arg(z+1)|<π4  
2 z:|z-1|>2 and |arg(z-1)|<π4  
3 z:|z+1|<2 and |arg(z+1)|<π2  
4 z:|z-1|<2 and |arg(z+1)|<π2  

Ans.

(1)

In the figure, we see that 

AB=AC=AD=2

 BCD is an arc of a circle with centre at A and radius 2. Shaded region is exterior part of this sector ABCDA.

 For any point represented by z on arc BCD we should have 

|z-(-1)|=2

and for shaded region, |z+1|>2               ...(i)

For shaded region, we also have 

-π4<arg(z+1)<π4

or |arg(z+1)|<π4             ...(ii)

From (i) and (ii), we get (1) is the correct option.