NIMCET 2015 — Mathematics PYQ
NIMCET | Mathematics | 2015The value of tan(87π) is
Choose the correct answer:
- A.
1−2
(Correct Answer) - B.
1+2
1−2
Explanation
1. Simplify the angle:
We can rewrite the angle 87π in terms of a known reference angle:
tan(87π)=tan(π−8π)
Using the identity tan(π−θ)=−tanθ:
tan(87π)=−tan(8π)
2. Find the value of tan(8π):
Let θ=8π, then 2θ=4π.
Using the half-angle formula tanθ=sin2θ1−cos2θ:
tan(8π)=sin4π1−cos4π
tan(8π)=211−21
tan(8π)=2122−1
tan(8π)=2−1
3. Final Calculation:
Substitute this back into our simplified expression:
tan(87π)=−(2−1)
tan(87π)=1−2
Conclusion:
The value is 1−2. The correct option is (a).
Explanation
1. Simplify the angle:
We can rewrite the angle 87π in terms of a known reference angle:
tan(87π)=tan(π−8π)
Using the identity tan(π−θ)=−tanθ:
tan(87π)=−tan(8π)
2. Find the value of tan(8π):
Let θ=8π, then 2θ=4π.
Using the half-angle formula tanθ=sin2θ1−cos2θ:
tan(8π)=sin4π1−cos4π
tan(8π)=211−21
tan(8π)=2122−1
tan(8π)=2−1
3. Final Calculation:
Substitute this back into our simplified expression:
tan(87π)=−(2−1)
tan(87π)=1−2
Conclusion:
The value is 1−2. The correct option is (a).

