Q.

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

1 π+32  
2 π–54  
3 π–32  
4 π+52  

Ans.

(2)

We have,

cot–1(1+tan2(2)–1tan(2))–cot–1(1+tan2(12)+1tan(12))

=cot–1(|sec(2)|–1tan(2))–cot–1(|sec(12)|+1tan(12))

=cot–1(–1–cos2sin2)–cot–1(1+cos(12)sin(12))

=cot–1(–2cos2(1)2cos(1)sin(1))–cot–1(2cos2(14)2cos(14)sin(14))

=cot–1(cot(–1))–cot–1(cot14)

=π–1–14=π–54.