△ABC外接圆的半径为1,圆心为O,且2OA→+AB→+AC→=0→,|OA→|=|AB→|,则CA→•CB→等于( )
Hello,I'm Bill. I like swimming.This is my father.He likes reading.This is my mother.She likes singing.This is my brother.He likes skating.This is my sister.She likes dancing.What about you?