10.11两题

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10.11两题

10.11两题
10.11两题
 

10.11两题
sin^21·+sin^22·+sin^23·+……+sin^289·
=1/2 (sin^21·+sin^22·+sin^23·+……+sin^289·+sin^21·+sin^22·+sin^23·+……+sin^289·)
=1/2 【(sin^21·++sin^289)·(sin^22·+88°)+(sin^23·+87°)+……+(sin^289·+sin^21)】
=1/2 [1+1+...+1]
=1/2×89
=44.5