For immune function, the following doses have been taken by mouth: 40 IU of vitamin D3 daily for 20 years to 100,000 IU of vitamin D3 bimonthly for 12 months, or 10,000 IU daily. For inflammatory bowel disease, 0.5 micrograms of alfacalcidol has been taken by mouth daily.
Intersecting lines. Two or more lines that meet at a point are called intersecting lines. That point would be on each of these lines. In Figure 1, lines l and m intersect at Q. Figure 1 Intersecting lines. Perpendicular lines. Two lines that intersect and form right angles are called perpendicular lines.
Skew lines are lines that are in different planes, are not parallel, and do not intersect. Parallel lines, as you will recall, are lines that are in the same plane and do not intersect. Also, remember that in mathematics, lines extend forever in both directions.