某居民小区内建有一块矩形草坪ABCD,AB=50米,BC=
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米,为了便于居民平时休闲散步,该小区物业管理公司将在这块草坪内铺设三条小路OE、EF和OF,考虑到小区整体规划,要求O是AB的中点,点E在边BC上,点F在边AD上,且∠EOF=90°,如图所示.
(1)设∠BOE=α,试将△OEF的周长l表示成α的函数关系式,并求出此函数的定义域;
(2)经核算,三条路每米铺设费用均为400元,试问如何设计才能使铺路的总费用最低?并求出最低总费用.
考点分析:
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已知向量
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,函数
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的图象的两相邻对称轴间的距离为
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,
(1)求ω;
(2)若
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时,求函数f(x)的单调递增区间;
(3)若
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,且f(x)=m有且仅有一个实根,求实数m的值.
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已知:
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是同一平面内的三个向量,其中
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(1)若
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,求
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的坐标;
(2)若
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与
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垂直,且
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与
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的夹角为120°,求
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.
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①y=tanx在定义域上单调递增;
②若锐角
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;
③f(x)是定义在[-1,1]上的偶函数,且在[-1,0]上是增函数,若
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,则f(sinθ)>f(cosθ);
④函数y=4sin(2x-
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)的一个对称中心是(
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,0);
其中真命题的序号为
.
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在直角坐标系xOy中,
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分别是与x轴,y轴平行的单位向量,若
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,且
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,则实数m=
.
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