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​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 cotθ=34, then find the value of sin3θ.\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:

cotθ=34\cot\theta=\frac{3}{4}​​

Find sin3θ\sin 3\theta​​

Formula Used:

sin3θ=3sinθ4sin3θ\sin 3\theta=3\sin\theta-4\sin^{3}\theta​​

Solution:

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

sin3θ =3(45)4(45)3 =125256125 =300256125 =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}​​

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