Last Activity: 12 Years ago
tan9x=tan(7x+2x)=(tan7x+tan2x)/(1-tan7xtan2x)
but given tan7xtan2x=1
so tan (7x+2x)=(tan7x+tan2x)/(1-tan7xtan2x)
that is =(tan7x+tan2x)/(1-1)
which is not defined.
so 9x=7x+2x=90degree
hence 9x=90degree
so 3x=30degree
1/root(3)....[ x=10 degree ]
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