The value of the expression [cosec (75° + θ) – sec (15° – θ) – tan (55° + θ) + cot (35° – θ)] is
(A) – 1 (B) 0 (C) 1 (D)
Answer. [B]
Solution. Given expression is :
[cosec(75° + q) – sec (15° – q) – tan (55° + q) + cot (35° – q)]
[cosec(90 – (15 – q)) – sec (15° – q) – tan (90 – (35 – q)) + cot (35° – q)]
{ we can write (75 + q) = (90 – (15 – q)) and (55 + q) = (90 – (35 – q))}
{ cosec (90 – q) = sec q and tan (90 – q) = cot q }
[sec(15 – q) – sec (15 – q) – cot (35 – q) + cot (35 – q)]=0
Hence option (B) is correct