" If "x cos A=1" And "tan A=y," On "x^(2)-y^(2)" What is the value of "

If cos x+ cosy =(4)/(5) and cos x- cos y =(2)/(7) , then the value of 14 tan ((x-y)/(2)) +5 cot ((x+y) /2)

If tan(x+ y)tan(x-y)=1 , then the value of tan x is:

If 2 cos theta=x+(1)/(x) and 2 cos phi=y+(1)/(y) then the value of cos (theta+phi) will be

If sin^(-1)x=tan^(-1)y what is the value of (1)/(x^(2))-(1)/(y^(2)) ?

If cos x = tan y , cos y = tan z , cos z = tan x , then the value of sin x is :

If sin^(-1) x = tan^(-1)y m what is the value of (1)/(x^(2))-(1)/(y^(2)) ?

If the sum of all value of x satisfying the system of equations tan x + tan y+ tan x* tan y=5 sin (x +y)=4 cos x * cos y is (k pi )/2 , where x in (0, (pi)/(2)) then find the values of k .