log(tan 2 degrees) + log(tan 4 degrees) + ... + log(tan 88 degrees) = ?
A. 1
B. 1/sqrt(2)
C. 0
D. -1
GATE 2015 · General Aptitude · Logarithms · medium
Answer: S = 0
- Convert sum to log of product: S = log(tan2 * tan4 * tan6 * ... * tan88)
- Identify complementary pairs: Pair (2, 88), (4, 86), ..., (44, 46): 22 pairs, each product = 1
- Compute the total product: tan2 * tan4 * ... * tan88 = 1
- Take the logarithm: S = log(1) = 0