﻿ Coursework 代写:弧度测量

# Coursework 代写:弧度测量

#### 2017-02-01 14:58

Coursework 代写:弧度测量

Radian is the SI unit for angle measure, and it has been used in many mathematical fields. One radian is the angle subtended at the center of a unit circle by an arc that is equal in length to 1. As the circumference of a unit circle is equal to 2π, a full circle is equal to 2π. Here π is a mathematical constant and is approximately equal to 3.1415926. Formally, π is the ratio of a circle's circumference to its diameter. Figure 3 shows the definition of radian by a unit circle.

Radian is invented by mathematicians in the 1700s, so it has a much shorter history than degree. The original motivation is that mathematicians want to measure angles rationally rather than choosing an arbitrary number like 360. They find that the ratio of a circle’s circumference to its diameter is a constant, represented by the Greek letter π. Then a full circle is defined as 2π radians. The definition of radian is beautiful, but it’s very challenging to compute π, because it cannot be expressed exactly as a ratio of two integers. Historically, people spend a lot of experience to calculate its approximate value. Thanks to the computer, this work has become very simple now.
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