If `cos^(2)theta-sin^(2)theta=(1)/(3)`, where, `theta(0 letheta le90^(@))`, the value of `co^(4)theta` is (यदि `cos^(2)theta-sin^(2)theta=(1)/(3)` और
If `cos^(2)theta-sin^(2)theta=(1)/(3)`, where, `theta(0 letheta le90^(@))`, the value of `co^(4)theta` is (यदि `cos^(2)theta-sin^(2)theta=(1)/(3)` और जहाँ `theta(0 letheta le90^(@))` का `co^(4)theta` मान ज्ञात करे)
A. `(1)/(3)`
B. `(2)/(3)`
C. `(1)/(9)`
D. `(2)/(9)`
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Correct Answer - a
`3sin theta+5cos theta=5`
`5sin theta-3 cos theta=x`
now,
`a^(2)+ b^(2)=p^(2)+q^(2)`
`3^(2)+5 ^(2)=5^(2)+x^(2)`
`9+25=25+x^ (2)`
`9=x^(2)`
`x=+-3`
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