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: Problem 1
Write the following as an imaginary number.
$${\sqrt{-72}}$$
Why is this not a complex number?
Problem 2
What kind of roots will the following quadratic function have?
$${4x-3x^2=10}$$


aligns: no