standard_description: 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.
problem_activity: Task
A preserved plant is estimated to contain $1$ microgram (a millionth of a gram) of
Carbon $14$.    The amount of Carbon 14 present
in the preserved plant is modeled by the equation
$$
f(t) = A\left(\frac{1}{2}\right)^{\frac{t}{5730}}
$$
where $t$ denotes time since the death of the plant, measured in years,
and $A$ is the amount of Carbon $14$ present in the plant at death, measured
in micrograms.
How much Carbon $14$ was present in the living plant assuming it died  $5000$ years ago?
How much Carbon $14$ was present in the living plant assuming it
died $10000$ years ago?
The half-life of Carbon $14$ is the amount of time it takes for half of the
Carbon $14$ to decay.  What half-life does the expression for  the function $f$
imply for Carbon $14$?


aligns: no