(sin(15-8)+cos15sin8)/(cos(15-8)-sin15sin8)
=[sin15cos8-cos15sin8+cos15sin8]/
[sin15con8+cos15cos8-sin15sin8]
=sin15cos8/cos15cos8
=tan15
(sin(15-8)+cos15sin8)/(cos(15-8)-sin15sin8)
=[sin15cos8-cos15sin8+cos15sin8]/
[sin15con8+cos15cos8-sin15sin8]
=sin15cos8/cos15cos8
=tan15