Periodic functions > Radians


Point P moves along the unit circle (circle with radius 1 ). The corresponding angle of rotation α is positive when you move counterclockwise, negative if when you move clockwise. It can have any value. The height h of P with respect to the horizontal axis is h = sin ( α ) .

For a more suitable graph we rather express the angle of rotation α = x in radians.
The angle then corresponds to the length of the arc on the unit circle (the blue part of the circle).
360 ° correponds to 2 π radians.

This standard sine graph is periodical with period 2 π .

Look at the applet: Sine graph

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