Question

What is the SI unit of angle?

Answer 1

Hint: Here in this question we have to mention the SI unit of an angle. Every measuring entity will have a standard unit. So first we know the definition of an angle and then the SI units of an angle. By defining the Si units of an angle we get a clear picture.

Complete answer: An angle is made up of two rays with a common endpoint. This end point is the vertex of the angle. The rays are the sides of the angle.

In this figure the angle is named as \[\angle ABC\] or \[\angle B\]
The measure of an angle is the amount of rotation made to get the terminal side from its initial side. There are several units of measuring angles.

The most commonly used units of measurements are:
1. Degree measure:
In this system an angle is measured in degrees, minutes and seconds. A complete rotation describes \[{360^ \circ }\]. \[{1^ \circ } = \dfrac{1}{{360}}\]th of a complete rotation.
A degree is further subdivided as
1 degree = 60 minutes, written as \[{1^ \circ } = 60'\]
1 minute = 60 seconds, written as \[1' = 60''\]
2. Radian measure:
In this system an angle is measured in radians.
A radian is an angle subtended at the centre of a circle by an arc whose length is equal to the radius of the circle.
The radian can be expressed in degrees. \[1\] radian = \[\dfrac{{{{180}^ \circ }}}{\pi }\]
Therefore the SI units of an angle are degree and radian.

Note:
 The International System of Units, is the modern form of the metric system. It is the only system of measurement with an official status in nearly every country in the world. A metric system of units based on the centimetre, gram, and second. For scientific and technical purposes these units have been replaced by SI units.