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
The circumference of a circle is
$$32\pi$$
cm. What expression represents the exact area of the circle? If needed, draw a diagram to assist you.
Problem 2
Find the area and perimeter of the colored part of each figure below. The figures are composed of small squares with side length 1 unit and curves that are an arc of a circle.
a.
[IMG]
b.
[IMG]
Problem 3
A semi-circle with a diameter of 6 cm sits on top of an isosceles trapezoid. Find the area of the entire figure.
[IMG]


aligns: no