1A50.10 - Radian Disk
The radian disk can be used in several ways. One way is to measure the radius and compare them to the outer arc. Note that when you measure the radius along the outer circumference of the circle you will get 3 equal areas plus that pesky .14 slice ( pi = 3.14 ) for each 180 degrees of the circle ( The entire circle is 2pi radians ). You can compare this to the other disk that just has 6 equal areas.
The disks can also be set on the screwdriver shaft through the hole in the middle so that it may be set up in a vertical fashion for easy turning.
The equilateral triangle arc can be used to show the radian angle is less than 60 degrees. By making one of the sides into an arc you have to compress the two other sides so that the angle is less than 60 degrees. This triangle is designed to be used with our radian disk.
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