10.11两题
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![10.11两题](/uploads/image/z/12044925-45-5.jpg?t=10.11%E4%B8%A4%E9%A2%98)
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