Table of Contents

## How do you Trisect an angle?

Some angles can be trisected by compass and straightedge. For example, a 180° angle can be trisected by constructing a pair of equilateral triangles. A 90° angle can be trisected by constructing a 30° angle on each of the two lines.

## How do you get the Trisect arc?

To trisect, do:

- Quadrisect the angle AOB, that is, divide it into four equal parts.
- Draw a circular arc (shown in orange) centered at O and radius 3/4 of OA.
- Swing an arc (not shown) of radius L centered at A′ and mark P′ its intersection with the arc A′B′, as shown.

**How do you bisect an angle without a compass?**

Bisecting angles without a protractor Place the compass on the point where one arc crosses an arm and draw an arc inside the angle. Without changing the compass width, repeat for the other arm so that the two arcs cross. Use a ruler to join the vertex to the point where the arcs intersect (D).

### Is it possible to Trisect a line?

A segment can be trisected in many ways. Most of the methods use similar triangles in some way. Below, two different ones are found. The first is a traditional trisecting of a segment.

### How do you bisect an angle by using only a ruler?

Connect points B and C with a straight line segment using the ruler. Measure a distance halfway between B and C. Denote the point halfway between as D. Draw a straight line segment from A to D, thus bisecting the angle.

**Which tool is used in constructing bisector of an angle?**

compass

Bisect the angle using a compass.

## How do you construct an angle trisection?

An angle trisection is a construction that takes an angle and creates an angle that has a measure of 1/3 of that original angle. Although we cannot construct an angle trisection with an unmarked straightedge and a compass, we can construct one with a marked straightedge and a compass, and it’s really not to hard to do!

## Is it possible to construct an angle trisection with an unmarked straightedge?

The teacher says that it was proven in the 19th century that it is impossible to construct an angle trisection using only an unmarked straightedge and a compass. Wait, a what? An angle trisection is a construction that takes an angle and creates an angle that has a measure of 1/3 of the original angle.

**How do you find the angle between a and B?**

On your straightedge, mark the distance between A and B (the radius of the circle), then maneuver it so that we can draw a line segment from B to a point D on the line parallel to BC that intersects the circle at a point E, and DE is the same length as your marked AB. The angle DBC trisects the angle ABC ( m ∠ DBC = (1/3) m ∠ ABC ).

### What is the oldest known trisection?

(Burton) The earliest known trisection was done by Hippias of Elis (ca 460-399 B.C.) using his quadratrix, the first curve other than the line and the circle seen in mathematics. (Dudley p. 6, Cajori p. 55, Boyer pp.68-69) To construct the quadratrix, start with a square and inscribe a quarter circle.