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问题: 数学题

sin²1°+sin²2°+sin²3°+……+sin²9°=?
答案是91/2
我需要详细解答过程

解答:

 sin^1°+sin^2°+sin^3°+...+sin^88°+sin^89°+sin^90°
= (sin^1°+sin^89°)+(sin^2°+sin^88°)+...+sin^45°+sin^90°
= (sin^1°+cos^1°)+(sin^2°+cos^2°)+...+(√2/2)^+1
= 1+1+...+1/2+1
= 44+1/2+1
= 91/2