1.

If `sin2A=2sinA cosAand sin20^(@)=K, " then the value of " cos20^(@)cos80^(@)cos160^(@)`=__________.A. KB. `-sqrt(1-k^(2)`C. `sqrt(1-k^(2))/(8)`D. `-sqrt(1-k^(2))/(8)`

Answer» Correct Answer - B
(i) Multiply and divide the given expression with `sin20^(@)`
(ii) Use `sin^(2) A = 2sinA cosA`.
`sin(180-A) = sinA`.


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