standard_description: Derive using similarity the fact that the length of the arc intercepted by an angle is proportional to the radius, and define the radian measure of the angle as the constant of proportionality; derive the formula for the area of a sector.
problem_activity: Given:
$${{f(x)}=\mathrm{cos}(2x)}$$
$${g(x)=-\mathrm{cos}(x)}$$
[IMG]
a.   Describe the period, amplitude, and midline of the function
$${f(x)}$$
.
b.   Where is
$${f(x)}=g(x)$$
over the domain of
$${0\leq x \leq 2\pi}$$
?


aligns: no