The graph of y = tan θ As the point P moves anticlockwise round the circle, the values of cos θ and sin θ change, therefore the value of tan θ will change. This graph has a period of 180°.

Cosine and sine of an angle θ are defined to be the x and y-coordinates of the point P on the unit circle with the property that the line from O to P makes and angle θ with the positve x-axis.

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. With ...

Revise trigonometric ratios of sine, cosine and tangent and calculate angles in right-angled triangles with this Bitesize GCSE Maths Edexcel guide.