Two lines are perpendicular if they intersect like a perfect T or cross. This is also known as a right angle.
To show that two lines are perpendicular we can use points on each of the lines and the symbol ⊥
So, to show the two given lines are perpendicular, we say AB⊥CD
Symbols used to show a right angle ( 90 °) are ∟or□
A C D
Lines meet at right angles
B
A right angle is an angle of 90 °, as in a corner of a square.
Constructing perpendicular lines using a compass and a ruler
1
Draw a line, l , and mark a point P on l. l
P 2
Place your compass point on P. Keeping the compass width fi xed, draw two arcs on l either side of P.
3
Increase the width of the compass a little bit. Place the compass point where the arc crossed the line on the right side and make a small arc above the line l .
4
Without changing the width of the compass, place the compass point where the arc crossed the line on the left side of P. Draw another arc such that the two arcs intersect.
4
5
With your straight edge, connect the intersection of the two small arcs to point P. This new line is perpendicular to the given line and passes through the point P.
Perpendicular bisector of a line segment
A bisector is something that cuts an object into two equal parts. It can be applied to angles and line segments.
A perpendicular bisector of a line segment [AB] is a line perpendicular to [AB] and passing through the midpoint of [AB] .
A Midpoint of line segment [AB] 46 Linking Thinking 1 B