`cos^-1(4/5)+tan^-1(3/5)=tan^-1(27/11)`

Prove that : 2 tan^-1 (1/2) + tan^-1 (1/5) =tan^-1 (23/11)

Prove that : tan^-1(3/4) + tan^-1(3/5)- tan^-1(8/19) = pi/4

Prove that: tan^(-1)(3/4)+tan^(-1)(3/5)-tan^(-1)(8/19)=pi/4

Prove that : tan^(-1)(1/2) + tan^(-1)(1/3) = tan^(-1)(3/5) + tan^(-1)(1/4) = pi/4

Prove that : tan^(-1)(1/2) + tan^(-1)(1/3) = tan^(-1)(3/5) + tan^(-1)(1/4) = pi/4

show that cos^(-1)""(4)/(5)+cot^(-1)""(5)/(3)=tan ^(-1)""(27)/(11) .

Which of the following is/are correct? tan[cos^(-1)(4)/(5)+tan^(-1)(2)/(3)]=(17)/(6)cos[tan^(-1)(1)/(3)+tan^(-1)(1)/(2)]=(1)/(sqrt(2))cos2tan^(-1)((1)/(3))+cos(tan^(-1)2sqrt(2))=(14)/(15)cos[2cos^(-1)(1)/(5)+sin^(-1)(1)/(5)]=-(2sqrt(6))/(6)

Show that 1/2 cos^-1 (3/5) = tan^-1 (1/2) =pi/4 - 1/2 cos^-1( 4/5)

tan^(-1)((4)/(7))-tan^(-1)((1)/(5))=tan^(-1)((1)/(3))

Show that , cos^(-1) 4/5 + cot^(-1) 5/3 = tan^(-1) 27/11