Prove that `cot^(-1) 7 + 2 cot^(-1)3 = pi/4`

Prove that : cot^(-1) 3 + cot^(-1).(3)/(4) = cot^(-1) .(1)/(3)

Prove that 2cot^(-1)5+ cot^(-1)7 + 2cot^(-1)8 =pi/4

Prove that cot((pi)/(4)-2cot^(-1)3)=7

prove that tan^(-1)x+cot^(-1)x=pi/2

Prove that : cot^(-1)7+cot^(-1)8+cot^(-1)18=cot^(-1)3

Prove that tan^(-1)(cot x)+cot^(-1)(tan x)=pi-2x

Solve : cot^(-1)2x+cot^(-1)3x=(pi)/(4)

Prove that : (i) tan^(-1) x + cot^(-1)( x+1) = tan^(-1) (x^(2)+x+1) (ii) cot^(-1) 3 + "cosec"^(-1) sqrt(5) = pi/4

Prove that cot^(-1)(3)-cot^(-1)(4)=cot^(-1)(13)