A perpendicular bisector is a line that divide another line into two equal measures and is perpendicular to the line it dissects. A triangle has three perpendicular bisectors, one for each side. To find the perpendicular bisector, which is not immediately visible, you need to measure a side to find the point that divides it into equal halves, and then draw a line that passes through that point and creates a right angle with the side.
- Measure a side
Find the length of a side of any triangle using a ruler. You need this value to find out where the midpoint lies on that side.
- Find the midpoint
Divide the side's length in half. From an endpoint of the same side, measure that half-length and mark it. That is the midpoint of the side.
- Construct the perpendicular line
Draw a line that forms a 90-degree angle with the side of the triangle and passes through its measured midpoint. Use a protractor to ensure that the angle you're creating is a perfect right angle. This line is the side's perpendicular bisector.
- Find the perpendicular bisectors for the other sides
Repeat the process for the other sides of the triangle. All triangles have three perpendicular bisectors, regardless of type or size.