NIMCET 2018 — Mathematics PYQ
NIMCET | Mathematics | 2018If sin θ = 3 sin (θ + 2α), then the value of tan (θ + α) + 2 tan α is
Choose the correct answer:
- A.
3
- B.
2
- C.
-1
- D.
0
(Correct Answer)
0
Explanation
Concept:
componendo and dividendo formula, we have
ba=a−ba+b
Trigonometric formula:
sin C + sin D = 2sin (C+D).sin (C - D)
sin C - sin D = 2sin (C+D).sin (C - D)
Calculations:
Given, sin θ = 3 sin (θ + 2α)
</span><br><span style="font-size: 14pt;">\frac{\sin θ}{\sin (θ + 2α)} = \frac{3}{1}
By componendo and dividendo formula, we have
\frac{\sin θ + \sin (θ + 2α)}{\sin θ - \sin (θ + 2α)} = \frac{3+1}{3-1}
We know that,
sinC+sinD=−2sin(C+D).sin(C−D) sinC-sinD=2sin(C+D).sin(C−D)
→−2sin(θ+2α)cosα=2
2cos(θ+2α)sinα
⇒−tan(θ+2α)cotα=2
⇒−tan(θ+2α)=2tanα
⇒ tan (θ+2α)+2 tan α=0
Explanation
Concept:
componendo and dividendo formula, we have
ba=a−ba+b
Trigonometric formula:
sin C + sin D = 2sin (C+D).sin (C - D)
sin C - sin D = 2sin (C+D).sin (C - D)
Calculations:
Given, sin θ = 3 sin (θ + 2α)
</span><br><span style="font-size: 14pt;">\frac{\sin θ}{\sin (θ + 2α)} = \frac{3}{1}
By componendo and dividendo formula, we have
\frac{\sin θ + \sin (θ + 2α)}{\sin θ - \sin (θ + 2α)} = \frac{3+1}{3-1}
We know that,
sinC+sinD=−2sin(C+D).sin(C−D) sinC-sinD=2sin(C+D).sin(C−D)
→−2sin(θ+2α)cosα=2
2cos(θ+2α)sinα
⇒−tan(θ+2α)cotα=2
⇒−tan(θ+2α)=2tanα
⇒ tan (θ+2α)+2 tan α=0

