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  3. 10th Class
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  5. Introduction to Trigonometry

10th Class Mathematics Introduction to Trigonometry Question Bank MCQs - Introduction to Trigonometry

  • question_answer
    If \[\cos \,A+{{\cos }^{2}}A=1\], then the value of \[{{\sin }^{2}}A+{{\sin }^{4}}A\]is

    A) 0

    B) 1

    C) -1

    D) 2

    Correct Answer: B

    Solution :

    Given, \[\cos A+{{\cos }^{2}}A=1\] \[\Rightarrow \,\,\,\,\cos A=1-{{\cos }^{2}}A\] \[\Rightarrow \,\,\,\cos A={{\sin }^{2}}A\] \[\left[ \because \,1-{{\cos }^{2}}A={{\sin }^{2}}A \right]\]                    … (i) We have to find the value of \[{{\sin }^{2}}A+{{\sin }^{4}}A\] \[\Rightarrow \,\,{{\sin }^{2}}A+{{\sin }^{4}}A\] \[\Rightarrow \,\,\cos A+{{\cos }^{2}}A\]                [from Eq (i)] \[\Rightarrow \,\,1\]


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