NTA Abhyas JEE Main2020MathematicsTrigonometric Ratios & IdentitiesPractice
If π 2 < α < 3 π 4 , then 2 tan ⁡ α + 1 c o s 2 α is equal to
Options
- A- 1 + tan α
- B- 1 - tan α
- C1 + tan α
- D1 - tan α
Correct answer
B. - 1 - tan α
Step-by-step solution
2 tan α + 1 c o s 2 α = 2 tan α + s e c 2 α = 2 tan α + 1 + t a n 2 α = 1 + tan α 2 = 1 + tan α Since, tan α < - 1 when π 2 < α < 3 π 4 ⇒ 1 + tan α < 0 ⇒ 1 + tan α = - 1 - tan α