options: Understand radian measure of an angle as the length of the arc on the unit circle subtended by the angle.

Use special triangles to determine geometrically the values of sine, cosine, tangent for π/3, π/4 and π/6, and use the unit circle to express the values of sine, cosines, and tangent for π–x, π+x, and 2π–x in terms of their values for x, where x is any real number.

Explain how the unit circle in the coordinate plane enables the extension of trigonometric functions to all real numbers, interpreted as radian measures of angles traversed counterclockwise around the unit circle.

Use the unit circle to explain symmetry (odd and even) and periodicity of trigonometric functions.
problem_activity: Problem 1
[IMG]
The radius of the circle above is
$$1$$
, and it is centered at the origin. This is called a “unit circle.” Find the coordinates of the point marked at
$${45^{\circ}}$$
.
Problem 2
[IMG]
The radius of the circle above is
$$1$$
, and it is centered at the origin. Find the coordinates of the point marked at
$$150^{\circ}$$
.


correct_option_index: 2

3