Q.

The value of cot1(1+tan2(2)1tan(2))cot1(1+tan2(12)+1tan(12)) is equal to          [2025]

1 π+32  
2 π54  
3 π32  
4 π+52  

Ans.

(2)

We have,

cot1(1+tan2(2)1tan(2))cot1(1+tan2(12)+1tan(12))

=cot1(|sec(2)|1tan(2))cot1(|sec(12)|+1tan(12))

=cot1(1cos2sin2)cot1(1+cos(12)sin(12))

=cot1(2cos2(1)2cos(1)sin(1))cot1(2cos2(14)2cos(14)sin(14))

=cot1(cot(1))cot1(cot14)

=π114=π54.