[問題] 數學
2.有一10x10公分的正方形
(a)設有101點在正方形內部,證明:必存在兩點,其距離小於等於根號2公分
(b)設有90點在正方形內部,證明:必存在兩點,其距離小於等於根號2公分
[提示]π>3 , 根號2<1.5
3.令S為球面x^2+y^2+z^2 = 1,L為直線{x=3,y=0},R為點(1,3,2)。考慮一動點P在球S上
移動,另一動點Q在L上移動,請問PQ+QR 的最小值為何?
我沒念過高中 但對高中數學頗有興趣
請會的人詳細說明 謝謝
3 網路上的解法
sol:令Q(3,0,a)
PQ+QR ={[(a^2+9)^0.5]-1}+[(a-2)^2+13)^0.5]
QR 我知道 應該就[(3,0,a)-(1,3,2)]^2
PQ 看不太懂~
後在就請懂的人解說了~
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※ 編輯: semmy214 (210.61.141.61), 09/15/2015 20:35:27
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