JEE Main2017MathematicsDeterminantsActual
If S = x ∈ 0 , 2 π : 0 cos ⁡ x - sin ⁡ x sin ⁡ x 0 cos ⁡ x cos ⁡ x sin ⁡ x 0 = 0 , then ∑ x   ∈   S tan π 3 + x is equal to:
Options
- A4 + 2 3
- B- 4 -2 3
- C- 2 + 3
- D-2 - 3
Correct answer
B. - 4 -2 3
Step-by-step solution
Given, 0 cos ⁡ x - sin ⁡ x sin ⁡ x 0 cos ⁡ x cos ⁡ x sin ⁡ x 0 = 0 Expanding the determinant, ⇒ 0 ( 0 - cos ⁡ x sin ⁡ x ) - cos ⁡ x 0 - cos 2 ⁡ x - sin ⁡ x sin 2 ⁡ x - 0 = 0 ⇒ cos 3 ⁡ x - sin 3 ⁡ x = 0 ⇒ tan 3 ⁡ x = 1 ⇒   tan ⁡ x = 1 ⇒ x = π 4 , 5 π 4     ⇒ S = π 4 ,   5 π 4 ∴ ∑ x   ∈   S tan π 3 + x = ∑ x