Learning Goal: Give students an opportunity to figure out how to calculate the length of an arc on their own before moving into formal notes and practice.

HSG.C.B.5 – 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.

TEKS

G.12(B) – apply the proportional relationship between the measure of an arc length of a circle and the circumference of the circle to solve problems

G.12(D) – describe radian measure of an angle as the ratio of the length of an arc intercepted by a central angle and the radius of the circle