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`sin^(4)theta-cos^(4)theta` हैA. `cos2theta`B. `-sin2theta`C. `sin2theta`D. `-cos2theta` |
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Answer» Correct Answer - d `sin^(4)theta-cos^(4)theta` `(sin^(2)theta-cos^(2)theta)(sin^(2)theta-cos^(2)theta)` `sin^(2)theta-cos^(2)theta(because sin^(2)theta+cos^(2)theta=1)` `rArr-(cos^(2)theta=sin^(2)theta)=-cos2 theta` `(because cos^(2)theta-sin^(2)theta=cos2theta)` |
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