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Prove that cot2θ+tan2θ=2sin4θ\cot 2\theta + \tan 2\theta = \frac{2}{\sin 4\theta}

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Q. Prove that cot2θ+tan2θ=2sin4θ\cot 2\theta + \tan 2\theta = \frac{2}{\sin 4\theta}
  1. Rewrite cot2θ\cot 2\theta: Rewrite cot2θ\cot 2\theta as 1tan2θ\frac{1}{\tan 2\theta} to have a common base for addition.\newlinecot2θ+tan2θ=1tan2θ+tan2θ\cot 2\theta + \tan 2\theta = \frac{1}{\tan 2\theta} + \tan 2\theta
  2. Combine terms over denominator: Combine the terms over a common denominator.\newline(1+tan2(2θ))/tan(2θ)=2sin(4θ)(1 + \tan^2(2\theta)) / \tan(2\theta) = \frac{2}{\sin(4\theta)}
  3. Use Pythagorean identity: Use the Pythagorean identity: 1+tan2(2θ)=sec2(2θ)1 + \tan^2(2\theta) = \sec^2(2\theta).
    sec2(2θ)tan2θ=2sin4θ\frac{\sec^2(2\theta)}{\tan 2\theta} = \frac{2}{\sin 4\theta}
  4. Express sec2(2θ)\sec^2(2\theta): Express sec2(2θ)\sec^2(2\theta) as 1cos2(2θ)\frac{1}{\cos^2(2\theta)} and simplify.1cos2(2θ)sin2θcos2θ=2sin4θ\frac{\frac{1}{\cos^2(2\theta)}}{\frac{\sin 2\theta}{\cos 2\theta}} = \frac{2}{\sin 4\theta}
  5. Simplify by multiplying: Simplify the left side by multiplying by cos2θsin2θ\frac{\cos 2\theta}{\sin 2\theta}. 1sin2θ=2sin4θ\frac{1}{\sin 2\theta} = \frac{2}{\sin 4\theta}
  6. Use double angle identity: Use the double angle identity for sine: sin4θ=2sin2θcos2θ\sin 4\theta = 2\sin 2\theta \cos 2\theta. 1sin2θ=22sin2θcos2θ\frac{1}{\sin 2\theta} = \frac{2}{2\sin 2\theta \cos 2\theta}
  7. Cancel out common terms: Cancel out the common terms.\newline1=1cos2θ1 = \frac{1}{\cos 2\theta}
  8. Take reciprocal to solve: Take the reciprocal of both sides to solve for cos2θ\cos 2\theta.cos2θ=1\cos 2\theta = 1
  9. Find values of 2θ2\theta: Find the values of 2θ2\theta that satisfy the equation cos2θ=1\cos 2\theta = 1.\newline2θ=2nπ2\theta = 2n\pi, where nn is an integer.
  10. Divide to solve for theta: Divide by 22 to solve for theta.\newlineθ=nπ\theta = n\pi, where nn is an integer.

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