NTA Abhyas JEE Main2020MathematicsTrigonometric Ratios & IdentitiesPractice
If tan 25 o = a , then the value of tan 205 o - tan 115 o tan 245 o + tan 335 o in terms of a is
Options
- A1 - a 2 1 + a 2
- B1 - a 2 a
- C2 a 1 + a 2
- D1 + a 2 1 - a 2
Correct answer
D. 1 + a 2 1 - a 2
Step-by-step solution
tan ⁡ 205 o - tan ⁡ 115 o tan ⁡ 245 o + tan ⁡ 335 o = tan ⁡ 25 o + cot ⁡ 25 o cot ⁡ 25 o - tan ⁡ 25 o = tan 2 ⁡ 25 o + 1 1 - tan 2 ⁡ 25 o = a 2 + 1 1 - a 2 = 1 + a 2 1 - a 2