#(sin(s+t))/(cos scos t) =tans+tant#
Left Side: #=(sin(s+t))/(cos scos t)#
#=(sins cos t+cos s sint)/(cos s cos t)#
#=(sins cos t)/(cos s cos t)+(cos s sint)/(cos s cos t)#
#=(sins cancel cos t)/(cos s cancel cos t)+(cancel cos s sint)/(cancel cos s cos t)#
#=sin s / cos s + sint/cost#
#=tan s + tan t#
#:.=#Right Side