and are said to be skew lines because they neither intersect nor are parallel. How many...

and are said to be skew lines because they neither intersect nor are parallel. How many planes are determined by

a) parallel lines AB and DC?

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b) intersecting lines AB and BC?

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c) skew lines AB and EF?

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d) lines AB, BC, and DC?

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e) points A, B, and F?

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f) points A, C, and H?

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g) points A, C, F, and H?