99 Percentile Qs Bank for JEE MainMathematicsSequences and Series
If tan π 9 , x , tan 7 π 18 are in arithmetic progression and tan π 9 , y , tan 5 π 18 are also in arithmetic progression, then | x - 2 y | is equal to :
Options
- A4
- B3
- C0
- D1
Correct answer
C. 0
Step-by-step solution
x = 1 2 tan π 9 + tan 7 π 18 and 2 y = tan π 9 + tan 5 π 18 so, x - 2 y = 1 2 tan π 9 + tan 7 π 18 - tan π 9 + tan 5 π 18 ⇒ | x - 2 y | = cot π 9 - tan π 9 2 - tan 5 π 18 = cot 2 π 9 - cot 2 π 9 = 0 astan 5 π 18 = cot 2 π 9 ; tan 7 π 18 = cot π 9