`If tan theta + tan phi = x "and" cot theta + cot phi = y, "prove that " cot ( theta + phi) = 1/x -1/y`

If tan theta+tan phi=a and cot theta+cot phi=b then cot(theta+phi)=

If tan theta + tan phi =a , and cot theta + cot phi =b , and theta - phi = alpha ne 0 , then

If (1 + tan theta) (1+ tan phi) = 2, then theta + phi =

If cot theta + tan theta = x and sec theta - cos theta = y then

If theta + phi = alpha and tan theta = k tan phi , then prove that sin (theta - phi) = (k - 1)/(k + 1) sin alpha .

If theta+phi=45^@ , prove that (cot theta-1) (cot phi-1) =2 .

If theta+phi=45^(@) ,prove that (cot theta-1)(cotphi-1)=2