arrow
arrow
arrow
​If cot⁡θ=34, then find the value of sin⁡3θ.\text{If } \cot \theta = \frac{3}{4}, \text{ then find the value of } \
Question

​If cot⁡θ=34, then find the value of sin⁡3θ.\text{If } \cot \theta = \frac{3}{4}, \text{ then find the value of } \sin 3\theta. ​​

A.

​44125\\\frac{44}{125}​​

B.

​117125\quad \frac{117}{125}​​

C.

​12581 \quad \frac{125}{81}​​

D.

​−117125 -\quad \frac{117}{125}​​

Correct option is A

Given:

cot⁡θ=34\cot\theta=\frac{3}{4}​​

Find sin⁡3θ\sin 3\theta​​

Formula Used:

​sin⁡3θ=3sin⁡θ−4sin⁡3θ\sin 3\theta=3\sin\theta-4\sin^{3}\theta​​

Solution:

From cot⁡θ=34,\cot\theta=\frac{3}{4},​take a right triangle with base = 3, perpendicular = 4, hypotenuse = 5.
So, sin⁡θ=45.\sin\theta=\dfrac{4}{5}.​​

sin⁡3θ =3(45)−4(45)3 =125−256125 =300−256125 =44125\sin 3\theta \\ \ \\=3\left(\frac{4}{5}\right)-4\left(\frac{4}{5}\right)^3 \\ \ \\=\frac{12}{5}-\frac{256}{125}\\ \ \\=\frac{300-256}{125}\\ \ \\=\frac{44}{125}​​

Free Tests

Free
Must Attempt

RRB NTPC UG Level PYP (Held on 7 Aug 2025 S1)

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

CBT-1 Full Mock Test 1

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

RRB Group D Full Mock Test 1

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
test-prime-package

Access ‘RRB NTPC’ Mock Tests with

  • 60000+ Mocks and Previous Year Papers
  • Unlimited Re-Attempts
  • Personalised Report Card
  • 500% Refund on Final Selection
  • Largest Community
students-icon
545k+ students have already unlocked exclusive benefits with Test Prime!
Our Plans
Monthsup-arrow