Can anyone help me verify this trig identity? I think I have most of it...just have a question about some.?

It's easier to see if you start with [(cosx cosy)-(sinx siny)]/ (cosx cosy) and go to (1-tanx tany). Just distribute the 1/(cosx cosy) through the brackets to get [(cosx cosy)/(cosx cosy)-(sinx siny)/(cosx cosy)]= (1-tanx tany)