#### Radian and degree | Unit circle definition of trig functions | Trigonometry | Khan Academy - By Khan Academy

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#### DESCRIPTION:

This video explains what a radian is and how we determine the radian measure of an angle. The key point here is that the radian measure of an angle is the length of the arc (in radius lengths) cut off by that angle (if the angle's vertex is on the center of the circle). You may ask: Won't the size of the circle affect the radian measure of an angle? A key feature of circles is that they are all similar (and thus, proportional). When we account for their larger size, we take into account the larger radius. As a result, the radian measure is the same for all circles (since the radian measure is how many radius lengths long the arc is).

#### OVERVIEW:

Radian and degree | Unit circle definition of trig functions | Trigonometry | Khan Academy is a free educational video by Khan Academy.It helps students in grades HS practice the following standards HSF.TF.A.1.

This page not only allows students and teachers view Radian and degree | Unit circle definition of trig functions | Trigonometry | Khan Academy but also find engaging Sample Questions, Apps, Pins, Worksheets, Books related to the following topics.

**
1. HSF.TF.A.1 :** Understand radian measure of an angle as the length of the arc on the unit circle subtended by the angle.

GRADES:

**HS**

STANDARDS:

**HSF.TF.A.1**