∵OA=OB,
∴△OAB是等腰三角形.
又∵AC=CB,∴OC⊥AB.
又∵OC是☉O的半径,
∴直线AB是☉O的切线.
83967908≈____万 3019456110≈____亿.
-- I hear local people are trying to prevent some businesses building factories here.
-- Yes. They say the place may be polluted if some factories _______in the future.
做自由落体的物体,先后经过空中的M,N两点时的速度分别为v1和v2,则下列说法中不正确的是( )