1.

Find the value of `sin^(2)5^(@)+ sin^(2)10^(@)+ sin^(2)15^(@)+* * * +sin^(2)90^(@)`.A. 8B. 9C. `(17)/(2)`D. `(19)/(2)`

Answer» Correct Answer - D
`sin^(2)5^(@)+ sin^(2)10^(@)+ sin^(2)15^(@)+* * * +sin^(2)90^(@)`.
`=(sin5^(@)+sin85^(@))+(sin^(2)10^(@)+sin^(2)80^(@))+* * *+sin^(2)45+sin^(2)90^(@)(sin85^(@)=cos5^(@))`
`=8((1)/(sqrt2))^(2)+=9+(1)/(2)=(19)/(2)`.


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