如图.一艘轮船按箭头所示方向行驶,C处有一灯塔,请你根据图中所标数据求∠ACB的大小.当轮船距离灯塔C最近时,∠ACB是

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  • ∠ABC=180°-70°=110°

    ∠ACB=180°-∠A-∠ABC

    =180°-30°-110°

    =40°

    当轮船距离灯塔C最近时,即BC⊥AB

    ∴∠ABC=90°

    ∠ACB=180°-∠A-∠ABC

    =180°-30°-90°

    =60°