Topic: Circle

Learning Objection: Students are able to identify and find the arc length and area of sector of circle.

Working in Progress >.> I edit later

1. 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;

2. What is Radian? Students can imagine a radian as the length of radius of the circle on the arc of circle is 1 radian and the full circle as 2π radian.

3. derive the formula for the area of a sector as

“Arc Length = θ × r” when θ is in radians

“Arc Length = (θ × π/180) × r ” when θ is in degrees