XAT 2017 — QA & DI Question 11
Trigonometric IdentitiesEasy
If 5° ≤ x° ≤ 15°, then the value of sin 30° + cos x° - sin x° will be:
Answer & solution
- A
Between -1 and -0.5 inclusive
- B
Between -0.5 and 0 inclusive
- C
Between 0 and 0.5 inclusive
- D
Between 0.5 and 1 inclusive
None of the above
Solution
sin 30° + cos x° – sin x° where 5° ≤ x° ≤ 15°.
For the given range, cos x > sin x
So, cos x° – sin x° > 0
Also, sin 30° = 0.5
sin 30° + cos x° – sin x° > 0.5
So, first four options are eliminated.
Hence, option (e).