Question

For which
value of acute angle costheeta
by1+ sin theeta
+cos theeta by 1- sin theeta
=4
is true

Answer 1

Given, →cosx1−sinx+cosx1+sinx=4

→cosx[11−sinx+11+sinx]=4

→cosx[1+sinx+1−sinx(1−sinx)⋅(1+sinx)]=4

→2cosx1−sin2x=4

→cosxcos2x=2

→cosx=12