Question -
Answer -
Let us consider LHS:
(tan 69o + tan 66o) / (1 –tan 69o tan 66o)
We know that, tan (A + B) = (tan A + tan B) / (1 – tanA tan B)
Here, A = 69o and B = 66o
So,
(tan 69o + tan 66o) / (1 –tan 69o tan 66o) = tan (69 + 66)o
= tan 135o
= – tan 45o
= – 1
= RHS
∴ LHS = RHS
Hence proved.