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How to Use a Protractor to Make a Graph

Scientific investigation requires the collection of data to prove a hypothesis. Data is often placed into a table format, but this can often make it more difficult to determine trends. A graph is a visual way of representing data and there are many types of graph.The most common graph plots points against linear axes, but this is not suitable for angular data. A polar plot is a graph that can be used to represent angular data and these can be plotted with the use of a ruler and protractor.

Things You'll Need

Protractor
Graph paper

Instructions

- 1
  Put the data into table format. Polar graphs have two variables which are the angle and length. These are normal written as (r, theta). Label the table headings with the correct units.
- 2
  Draw a horizontal line onto the graph paper. The line will indicate the zero degree mark. Mark the left of the the line "0." This is the origin.
- 3
  Align the center of the protractor with the left side of the horizontal line. Find the angle that corresponds to the first point and make a mark along that direction. The second coordinate that is plotted is the length. Place the ruler between the origin and the angle just measured. Plot a point at the distance corresponding to the coordinate. For example, if a polar coordinate is (45 degrees, 5 cm), then a point is plotted at 45 degrees, at a distance of 5 cm from the origin.
- 4
  Repeat the process for each of the tabulated values.

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