A unit circle is a circle with a radius equal to one (1) unit.[br][br]The circle is portioned into sectors based on the special right triangles [b]30°-60°-90°[/b] and [b]45°-45°-90°[/b]. These are the grey lines within the circle.[br][br]To see the [color=#1551b5]Degree measures[/color] check the [b]Degrees[/b] check box. [color=#c51414]Radian measures[/color] use the [b]Radian[/b] check box. When you select the [color=#0a971e]Coordinate value[/color], these are the cosine and sine values of the special right triangles [b]30°-60°-90°[/b] and [b]45°-45°-90°[/b]. Use the "[b]tri-[/b]" sliders to view how these [color=#1551b5]special right triangles[/color] fit on the unit circle. See Unit Circle Triangles for additional information.[br][br]Select each check box separately to see and learn the values described. [color=#c51414]Memorize the whole Unit Circle[/color].

Radians measure is determined by the number of radii that lay on the circumference of the circle.[br][br]The coordinates are the cosine and sine of the angles formed. The [b]cosine[/b] is always the [b]x-value[/b] laying on the [b]x-axis[/b]. The [b]sine[/b] is the always the [b]y-value[/b] laying on the [b]y-axis[/b]. The [b]signs[/b] of the [b]coordinate values[/b] follow the same rule used by the [b]quadrants[/b] of the coordinate system.[br][br]Finger [color=#1551b5]Mnemonics[/color] can help you remember these values. [color=#1551b5]Memory triggers[/color] can assist in using function arithmetic.[br][br]This applet can be used by teachers in a demonstration mode in the classroom or teachers can have students load it on their own computers with a worksheet to be complete for a grade.