InterviewSolution
Saved Bookmarks
| 1. |
Prove that:`tan^(-1)1/5+tan^(-1)1/7+tan^(-1)1/3+tan^(-1)1/8=pi/4` |
|
Answer» LHS=`tan^(-1)""(1)/(5)+tan^(-1)""(1)/(7)+ tan^(-1)""(1)/(3)+tan^(-1)""(1)/(8)` `tan^(-1)""((1)/(5)+(1)/(7))/(1-(1)/(5)xx(1)/(7))+tan^(-1)""((1)/(3)+(1)/(8))/(1-(1)/(3)xx(1)/(8))` `=tan^(-1)""((7+5)/(35))/((35-1)/(35))+tan^(-1)""(11)/(23)` `=tan^(-1)""((6)/(17)+(11)/(23))/(1-(6)/(17)xx(11)/(23))=tan^(-1)""((138+187)/(391))/((391-66)/(391))` `tan^(-1)""(352)/(325)=tan^(-1)1=(pi)/(4)`= RHS Hence Proved |
|