In high school, you probably learned that trigonometric functions – like sine, cosine and tangent ... (These are only the same value in the case of a unit circle!) This is why the square ...

Graphs of Sine and Cosine 1.2 An applet illustrating how the graphs of sine and cosine are related to the unit circle. Transformations of Functions 1.3 An applet illustrating how transformations ...

Part of that is the way it's taught. Students are taught the "unit circle" and its relationship to trigonometry, but many fail to make the leap on how crucial circles are for trig functions.

This circle has the centre at the origin and a radius of 1 unit. The point P can move around ... and the \(y\)-coordinate is \(\sin{\theta}\). As the point P moves anticlockwise around the circle ...