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  1. If tan (A – B) = x, then the value of x is
    1. (tanA + tan B)
      (1 - tanA tanB)
    2. (tanA + tan B)
      (1 + tanA tanB)
    3. (tanA - tan B)
      (1 - tanA tanB)
    4. (tanA - tan B)
      (1 + tanA tanB)
Correct Option: D

sin (A – B) = sinA . cosB – cosA . sinB
cos (A – B) = cosA . cosB + sinA . sinB

sin(A - B)
cos(A - B)

=
sinA.cosB - cosA.sinB
⇒ tanA
cosA.cosB - sinA.sinB

=  
sinA.cosA
  -
cosA.sinB
cosA.cosBcosA.cosB
cosA.cosB
+
cosA.cosB
cosA.cosBcosA.cosB

+ (Dividing numerator and denominator by cosA cosB)
=
tanA - tanB
1 + tanA.tanB



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