Trigonometric Equations Questions

What is the General Solution of \(tan \theta\) = \(tan \alpha\) ?

Solution : The general solution of \(tan \theta\) = \(tan \alpha\) is given by \(\theta\) = \(n\pi + \alpha\),  n \(\in\) Z. Proof : We have, \(tan \theta\) = \(tan \alpha\) \(\implies\)  \(sin \theta\over cos \theta\) = \(sin \alpha\over cos \alpha\) \(\implies\)  \(sin \theta cos \alpha\) – \(cos \theta sin \alpha\) = 0 \(\implies\)  \(sin …

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What is the General Solution of \(cos \theta\) = \(cos \alpha\) ?

Solution : The general solution of \(cos \theta\) = \(cos \alpha\) is given by \(\theta\) = \(2n\pi \pm \alpha\),  n \(\in\) Z. Proof : We have,  \(cos \theta\) = \(cos \alpha\) \(\implies\)  \(cos \theta\) – \(cos \alpha\) = 0 \(\implies\)   -\(2 sin ({\theta + \alpha\over 2}) sin({\theta – \alpha\over 2})\) = 0 \(\implies\)  \(sin ({\theta …

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What is the General Solution of \(sin \theta\) = \(sin \alpha\) ?

Solution : The general solution of \(sin \theta\) = \(sin \alpha\) is given by \(\theta\) = \(n\pi + (-1)^n \alpha\),  n \(\in\) Z. Proof : We have,  \(sin \theta\) = \(sin \alpha\) \(\implies\)  \(sin \theta\) – \(sin \alpha\) = 0 \(\implies\)   \(2 sin ({\theta – \alpha\over 2}) cos({\theta + \alpha\over 2})\) = 0 \(\implies\)  \(sin …

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Solve : \(\sqrt{3} cos \theta\) + \(sin \theta\) = \(\sqrt{2}\)

Solution : We have, \(\sqrt{3} cos \theta\) + \(sin \theta\) = \(\sqrt{2}\)            ………….(i) This is of the form \(a cos\theta\) + \(b sin \theta\) = c, where a = \(\sqrt{3}\), b = 1 and c = \(\sqrt{2}\). Let a = \(r cos\alpha\) and b = \(r sin\alpha\). Then, \(\sqrt{3}\) = …

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What is the General Solution of \(sin^2 \theta\) =\(sin^2 \alpha\) ?

Solution : The general solution of \(sin^2 \theta\) = \(sin^2 \alpha\) is given by \(\theta\) = \(n\pi \pm \alpha\), n \(\in\) Z. Proof : We have, \(sin^2 \theta\) =\(sin^2 \alpha\) \(\implies\)  \(2 sin^2 \theta\) =\(2 sin^2 \alpha\) \(\implies\)  \(1 – cos 2\theta\) = \(1 – cos 2\alpha\) \(\implies\)   \(cos 2\theta\) = \(cos 2\alpha\) \(\implies\)  \(2\theta\) …

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What is the General Solution of \(cos^2 \theta\) =\(cos^2 \alpha\) ?

Solution : The general solution of \(cos^2 \theta\) = \(cos^2 \alpha\) is given by \(\theta\) = \(n\pi \pm \alpha\), n \(\in\) Z. Proof : We have, \(cos^2 \theta\) =\(cos^2 \alpha\) \(\implies\)  \(2 cos^2 \theta\) =\(2 cos^2 \alpha\) \(\implies\)  \(1 + cos 2\theta\) = \(1 + cos 2\alpha\) \(\implies\)   \(cos 2\theta\) = \(cos 2\alpha\) \(\implies\)  \(2\theta\) …

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What is the General Solution of \(tan^2 \theta\) =\(tan^2 \alpha\) ?

Solution : The general solution of \(tan^2 \theta\) = \(tan^2 \alpha\) is given by \(\theta\) = \(n\pi \pm \alpha\), n \(\in\) Z. Proof : We have, \(tan^2 \theta\) =\(tan^2 \alpha\) \(\implies\)  \(1 – tan^2\theta\over 1 + tan^2 \theta\) =\(1 – tan^2\alpha\over 1 + tan^2 \alpha\) \(\implies\)   \(cos 2\theta\) = \(cos 2\alpha\) \(\implies\)  \(2\theta\) = \(2n\pi …

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What is the General Solution of \(Cot \theta\) = 0 ?

Solution : The general solution of \(cot \theta\) = 0 is given by \(\theta\) = \((2n + 1){\pi\over 2}\), n \(\in\) Z. Proof : We have, \(cot \theta\) = \(OM\over PM\) \(\therefore\)   \(cot \theta\) = 0 \(\implies\)  \(OM\over PM\) = 0 \(\implies\) OM = 0 \(\implies\)  OP coincides with OY or OY’ \(\implies\)  \(\theta\) = …

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What is the General Solution of \(Cos \theta\) = 0 ?

Solution : The general solution of \(cos \theta\) = 0 is given by \(\theta\) = \((2n + 1){\pi\over 2}\), n \(\in\) Z. Proof : We have, \(cos \theta\) = \(PM\over OP\) \(\therefore\)   \(cos \theta\) = 0 \(\implies\)  \(OM\over OP\) = 0 \(\implies\) OM = 0 \(\implies\)  OP coincides with OY or OY’ \(\implies\)  \(\theta\) =  …

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What is the General Solution of \(Tan \theta\) = 0 ?

Solution : The general solution of \(tan \theta\) = 0 is given by \(\theta\) = \(n\pi\), n \(\in\) Z. Proof : We have, \(tan \theta\) = \(PM\over OM\) \(\therefore\)   \(tan \theta\) = 0 \(\implies\)  \(PM\over OM\) = 0 \(\implies\) PM = 0 \(\implies\)  OP coincides with OX or OX’ \(\implies\)  \(\theta\) = 0, \(\pi\), \(2\pi\), …

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