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难度系数:

1.

中,分别为的中点,,求的长为(  )


A:

B:

C:

D:

  • 提示1PHA+6K6+IDxpbWcgc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC8wMS9DQy9yQkFDRkZNTlRwR1MxQmEzQUFBQ1VWeWZUQ0EwNjUucG5nIiBkYXRhLWNrZS1zYXZlZC1zcmM9Imh0dHBzOi8vcDEucWluZ2d1by5jb20vRzEvTTAwLzAxL0NDL3JCQUNGRk1OVHBHUzFCYTNBQUFDVVZ5ZlRDQTA2NS5wbmciIGhlaWdodD0iMjEiIHdpZHRoPSIxMTgiPu+8jOeEtuWQjuWIqeeUqOWLvuiCoeWumueQhuihqOekukFEwrLvvIxCRcKy77yM5pW055CG5b6X5Ye6YcKyK2LCsueahOWAvO+8jOi/m+iAjOaxguWHukFCPC9wPg==