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Question

If $3(\sin^2\theta + \text{cosec}^2\theta) = 10$, then the value of $\cot^6\theta + \text{cosec}^6\theta$ is:

The correct answer is
35

Trigonometry: Solving for $\cot^6\theta + \text{cosec}^6\theta$

We are given the equation: $3(\sin^2\theta + \text{cosec}^2\theta) = 10$

Simplify the Given Equation

  1. Divide both sides by 3: $ \sin^2\theta + \text{cosec}^2\theta = \frac{10}{3} $
  2. Use the identity $ \sin^2\theta = \frac{1}{\text{cosec}^2\theta} $: $ \frac{1}{\text{cosec}^2\theta} + \text{cosec}^2\theta = \frac{10}{3} $
  3. Let $ x = \text{cosec}^2\theta $. The equation becomes: $ \frac{1}{x} + x = \frac{10}{3} $
  4. Multiply by $ 3x $ to clear fractions: $ 3 + 3x^2 = 10x $
  5. Rearrange into a quadratic equation: $ 3x^2 - 10x + 3 = 0 $
  6. Factor the quadratic equation: $ (3x - 1)(x - 3) = 0 $
  7. The possible values for $ x $ are $ x = 3 $ or $ x = \frac{1}{3} $.
  8. Since $ x = \text{cosec}^2\theta $, and $ \text{cosec}^2\theta \ge 1 $, we must have $ \text{cosec}^2\theta = 3 $.

Calculate $\cot^2\theta$

Use the trigonometric identity $ \cot^2\theta = \text{cosec}^2\theta - 1 $. Substituting the value of $ \text{cosec}^2\theta $: $ \cot^2\theta = 3 - 1 = 2 $

Calculate the Final Expression

We need to find the value of $ \cot^6\theta + \text{cosec}^6\theta $. This can be written as $ (\cot^2\theta)^3 + (\text{cosec}^2\theta)^3 $. Substitute the values we found: $ \cot^2\theta = 2 $ and $ \text{cosec}^2\theta = 3 $. $ (\cot^2\theta)^3 + (\text{cosec}^2\theta)^3 = (2)^3 + (3)^3 $ $ = 8 + 27 $ $ = 35 $

Therefore, the value of $ \cot^6\theta + \text{cosec}^6\theta $ is 35.

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Important Questions from Trigonometric Identities

  1. What is cos 2β equal to ?

  2. What is the value of sec2γ?

  3. On simplifying \(\frac{{{{\sin }^3}{\rm{A}} + \sin 3{\rm{\;A}}}}{{\sin {\rm{A}}}} + \frac{{{{\cos }^3}{\rm{A}} - \cos 3{\rm{\;A}}}}{{\cos {\rm{A}}}}\) we get

  4. (1 – sin A + cos A) 2is equal to

  5. What is \(\frac{{\cos {\rm{\theta }}}}{{1 - \tan {\rm{\theta }}}} + \frac{{\sin {\rm{\theta }}}}{{1 - \cot {\rm{\theta }}}}\) equal to?

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