The unit circle is the circle of radius one centered at the origin (0, 0) in the Cartesian coordinate system.

Consider any point on the circumference of the circle P(x,y).

The line OP makes theta degrees of angle with x axis. then the x coordinate of the point P is simply cos ( theta) and the y coordinate of the point P is sin(theta).

**Use the interactive graph given below: **Hold and drag the point P on the circumference of the circle to change the angle and observe the relationship between the coordinates and the angle with x axis which the line segment OP makes.

**Use the interactive graph given below: **Hold and drag the point P on the circumference of the circle to change the angle and observe the relationship between the coordinates and the angle with x axis which the line segment OP makes.

**Skill builder questions**

Practice worksheet – 1 | Angle of any magnitude |

Practice worksheet – 2 | Convert degree – radian |

Practice worksheet – 3 | Measure angle worksheet |