Question #0eae5

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Answer 1 · 2017-11-09T07:28:19

See the proof below

The left hand side is

#LHS=(cos11+sin11)/(cos11-sin11)#

Divide numerator and denominator by #cos11#

#LHS=(cos11/cos11+sin11/cos11)/(cos11/cos11-sin11/cos11)#

#=(1+tan11)/(1-tan11)#

Since #tan45=1#

Therefore,

#LHS=(tan45+tan11)/(1-tan45tan11)#

We know that

#tan(a+b)=(tana+tanb)/(1-tanatanb)#

So,
#(tan45+tan11)/(1-tan45tan11)=tan56#

#=RHS#

#QED#