What is a Radian?
“A radian is an angular measurement that is equal to the angle formed at the center of a circle by two radii cutting off an arc whose length is equal to the radius.” That is a direct quote from the Webster’s New World Edition Dictionary. Look at it as a slice of pie in which the “outer rounded side” is equal to the two straight sides. The angle at the pointy end is one radian. How do you find this great angle? OK, radian = 2 pi r/r is the standard formula. So a circle with a five inch radius becomes (2 * 3.1416 * 5)/5 = 6.2832 radians to a circle of 360 degrees. By dividing 360 degrees by 6.2832, you find that there are 57.2956 degrees in a radian. You also know that there are 6283.2 milradian in a circle. Either of these can give you the number of minutes of angle in a milradian or mil. That magic number is 3.438, which is commonly rounded to 3.44. This is a mil is a mil is a mil. There is no difference in Marine or Army mils. The problem is the military compass. The military compass
A radian is a unit of measurement defined as 180/π°, or roughly 57.2958°. Sometimes abbreviated as rad or as the subscript c, standing for “circular measure,” the radian is the standard unit of measurement for angles in mathematics. The radian was first conceived of by English mathematician Roger Cotes in 1714, though he did not name the unit of measurement. The word radian first appeared in print in 1873. Originally, the radian was considered a supplementary unit in the International System of Units (SI), but supplementary units were abolished in 1995 and are now known as derived units. The radian is derived from the SI base unit meter (m), being equal to m·m-1, or m/m. Because the meters cancel each other out in the definition of the radian, the radian is considered dimensionless, and for this reason, radians are often simply written as a number, with no unit symbol. The radian is the angle formed by two radii, lines from the center to the outside circumference of a circle, where the
