A:−15
B:15
C:−152
D:152
768+2815=( )
若⊙O的半径长是4cm,圆外一点A与⊙O上各点的最远距离是12cm,则自A点所引⊙O的切线长为( )
句子改错。
I have a headache I didn't sleep good last night.
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