本课配套习题挑战模式1/4

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1.

点B是点A(1,2,3)在坐标平面内的射影,则OB等于(     )


A:

B:

C:

D:

  • 提示1PHA+5qC55o2u6aKY5oSP5Y+v5b6XPGltZyBzcmM9Imh0dHBzOi8vcDIucWluZ2d1by5jb20vRzEvTTAwLzQ3LzVCL3JCQUNKMVRaV2EtVDAyNmpBQUFDWlpQOU5jSTQ2Ni5wbmciIGRhdGEtY2tlLXNhdmVkLXNyYz0iaHR0cHM6Ly9wMi5xaW5nZ3VvLmNvbS9HMS9NMDAvNDcvNUIvckJBQ0oxVFpXYS1UMDI2akFBQUNaWlA5TmNJNDY2LnBuZyIgaGVpZ2h0PSIyMSIgd2lkdGg9IjYyIj7vvIw8L3A+
  • 提示2PHA+PGltZyBzcmM9Imh0dHBzOi8vcDEucWluZ2d1by5jb20vRzEvTTAwLzdCL0NCL3JCQUNFMVRaV2JERDB5eGxBQUFHa2gwQ0ZoODY5OC5wbmciIGRhdGEtY2tlLXNhdmVkLXNyYz0iaHR0cHM6Ly9wMS5xaW5nZ3VvLmNvbS9HMS9NMDAvN0IvQ0IvckJBQ0UxVFpXYkREMHl4bEFBQUdraDBDRmg4Njk4LnBuZyIgaGVpZ2h0PSIyNyIgd2lkdGg9IjEyNiI+PC9wPg==