10th Class Mathematics Introduction to Trigonometry Question Bank Trigonometry

  • question_answer
    If \[\sin \theta +\cos \theta =\sqrt{2}\] and \[\theta \] is acute, then \[\tan \theta \] is equal to

    A) \[\frac{1}{\sqrt{3}}\]

    B) \[1\]

    C) \[\sqrt{3}\]

    D) \[\infty \]

    Correct Answer: B

    Solution :

     Given, \[\sin \theta +\cos \theta =\sqrt{2}\] or            \[\sin \theta .\frac{1}{\sqrt{2}}+\cos \theta .\frac{1}{\sqrt{2}}=1\] or            \[\sin \theta \,\cos {{45}^{o}}+\cos \theta sin{{45}^{o}}=1\] or            \[\sin (\theta +{{45}^{o}})=1=\sin {{90}^{o}}\] or            \[\theta +{{45}^{o}}={{90}^{o}}\] or            \[\theta ={{45}^{o}}\] \[\therefore \]  \[\tan \theta =\tan {{45}^{o}}=1\]


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