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Perpendicular Lines wgc2010.org Topical overview | Geometry synopsis | MathBits" Teacher resources Terms that Use call Person: Donna Roberts

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NOTE: The tactics for proofs that the theorems proclaimed on this page are "discussed" only. A "formal" proof would call for that more details it is in listed.

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Perpendicular lines (or segments) actually kind four ideal angles, even if only one of the ideal angles is marked with a box.

The statement above is actually a theorem which is disputed further down on this page.

You are watching: Lines that intersect to form right angles

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There room a pair of typical sense concepts relating come perpendicular lines:


1. The shortest street from a allude to a heat is the perpendicular distance. any distance, various other than the perpendicular distance, from allude P to line m will end up being the hypotenuse that the right triangle. It is well-known that the hypotenuse the a appropriate triangle is the longest next of the triangle.
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2. In a plane, through a point not ~ above a line, over there is one, and only one, perpendicular come the line.

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If us assume there room two perpendiculars to line m from suggest P, us will develop a triangle containing two appropriate angles (which is no possible). Our presumption of two perpendiculars from suggest P is not possible.

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Perpendicular present can additionally be connected to the ide of parallel lines:


3. In a plane, if a heat is perpendicular to among two parallel lines, it is likewise perpendicular to the various other line. In the diagram at the right, if m | | n and also tm, climate t n. The two marked right angles are matching angles for parallel lines, and are because of this congruent. Thus, a best angle likewise exists where line t intersects heat n.
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In the diagram in ~ the right, if tm and sm,then t | | s.Since t and s space each perpendicular to heat m, we have actually two right angles whereby the intersections occur. Due to the fact that all ideal angles are congruent, we have actually congruent corresponding angles which create parallel lines.


When 2 lines room perpendicular, there are four angles created at the point of intersection. It renders no difference "where" you label the "box", since every one of the angle are best angles.

By upright angles, the 2 angles across from one one more are the same size (both 90º). By using a linear pair, the surrounding angles add to 180º, making any type of angle adjacent to the box another 90º angle.


When two nearby angles form a direct pair, their non-shared sides kind a straight line (m). This tells united state that the steps of the two angles will include to 180º. If these 2 angles additionally happen to be congruent (of equal measure), we have two angles of the very same size adding to 180º. Each angle will certainly be 90º making m n.
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In the diagram in ~ the left,