Question 292706
{{{tan(x+y)=

sin(x+y)/cos(x+y)= (sin(x)cos(y)+cos(x)sin(y))/(cos(x)cos(y)-sin(x)sin(y))=
((sin(x)cos(y))/(cos(x)cos(y))+(cos(x)sin(y))/(cos(x)cos(y)))/((cos(x)cos(y))/
(cos(x)cos(y))-(sin(x)sin(y))/(cos(x)cos(y)))=((sin(x)cross(cos(y)))/
(cos(x)cross(cos(y)))+(cross(cos(x))sin(y))/(cross(cos(x))cos(y)))/
((cross(cos(x)cos(y)))/(cross(cos(x)cos(y)))-(sin(x)sin(y))/(cos(x)cos(y)))

= (sin(x)/cos(x)+sin(y)/cos(y))/(1-(sin(x)/cos(x))(sin(y)/cos(y)))

= (tan(x)+tan(y))/(1-tan(x)tan(y))

}}}