JEE Advanced2009MathematicsTrigonometric EquationsActual
For 0 < < 2 , the solution(s) of _ m=1 ^6 cosec [ + (m-1) 4 ] cosec ( + m 4 )=4 2 is/are
Options
- A4
- B6
- C12
- D5 12
Correct answer
C. 12
Step-by-step solution
For 0 < < 2 , array r _ m=1 ^6 cosec [ + (m-1) 4 ] cosec ( + m 4 ) =4 2 _ m=1 ^6 [ + m 4 - ( + (m-1) 4 ) ] 4 ( + (m-1) 4 ) ( + m 4 ) =4 2 array array r _ m=1 ^6 ( + (m-1) 4 )- ( + m 4 ) 1 / 2 =4 2 array aligned & _ m=1 ^6 [ ( + (m-1) 4 ) . & .- ( + m 4 ) ]=4 & ( )- ( + 4 )+ ( + 4 ) & - ( + 2 4 )+ + ( + 5 4 ) & - ( + 6 4 )=4 & - ( 3 2 + )=4 & + =4 & ^2 -4 +1=0 & ( -2)^2-3=0 & ( -2+ 3 )( -2- 3 )=0 & =2- 3 or & =2+ 3 & = 12 ; = 5 12 (0, 2 ) & aligned