In Geometry
400
intersection of the lines drawn perpendicular to each side of the triangle through its midpoint
Perpendicular lines passing through a point are at right angles to each other.
Yes, but only in principle. In practice, you won't live long enough. Putting it in more positive terms: No matter how many lines have already been drawn perpendicular to a given line [segment], there's always enough room for a lot more of them.
Any line that is not parallel to the given lines. The transversal that contains the shortest distance between the two parallel lines, is perpendicular to them.
Infinity
400
Lines are parallel if they are perpendicular to the same line. Since the lines m and l are parallel (given), and the line l is perpendicular to the line p (given), then the lines m and p are perpendicular (the conclusion).
They are perpendicular lines
One.
Parallel
intersection of the lines drawn perpendicular to each side of the triangle through its midpoint
Infinite lines because a circle has infinite lines of symmetry.
Magnetic north (which is a little different from north. as defined as the meeting point of all lines drawn perpendicular to the equator and passing through the northern hemisphere)
Perpendicular lines passing through a point are at right angles to each other.
Yes, but only in principle. In practice, you won't live long enough. Putting it in more positive terms: No matter how many lines have already been drawn perpendicular to a given line [segment], there's always enough room for a lot more of them.
Any line that is not parallel to the given lines. The transversal that contains the shortest distance between the two parallel lines, is perpendicular to them.