Solution :
The formula of tan (A – B) is tanA–tanB1+tanAtanB.
Proof : We have,
tan (A – B) = sin(A–B)cos(A–B)
Using sin (A – B) and cos (A – B) formula,
tan (A – B) = sinAcosB–cosAsinBcosAcosB+sinAsinB
Dividing the numerator and denominator by cos A cos B,
tan (A – B) = tanA–tanB1+tanAtanB.