# If $A=35^{\circ},B=15^{\circ}$ and $C=40^{\circ}$, then $tan A. \tan B+\tan B. \tan C+\tan C. \tan A=$

$\begin {array} {1 1} (1)\;0 & \quad (2)\;1 \\ (3)\;2 & \quad (4)\;3 \end {array}$

(2) 1
answered Nov 7, 2013 by