Arc Length and Sector Area

Understand arc length and sector area.

Lesson 5 of 53 parts Practice Flashcards

1/3

Arc Length

Objective: Apply arc length.

Arc length is (θ/360°)×2πr for central angle θ.

Worked examples

Try itFind arc length for radius 3 and central angle 90°. Give an exact answer in π units.Show answer

1.5π. A quarter of circumference 2πr is πr/2.

Swipe sideways to move between sections

Objective: Apply arc length.

Arc length is (θ/360°)×2πr for central angle θ.

Worked examples

Try itFind arc length for radius 3 and central angle 90°. Give an exact answer in π units.Show answer

1.5π. A quarter of circumference 2πr is πr/2.

Objective: Apply sector area.

Sector area is (θ/360°)×πr².

Worked examples

Try itFind sector area for radius 6 and central angle 90°. Give an exact answer in π units.Show answer

9π. A 90° sector is one fourth of area πr².

Objective: Apply fraction of a circle.

The fraction of the circle is θ/360° for a central angle θ.

Worked examples

Try itWhat fraction of a circle is a central angle of 12°?Show answer

1/30. Fraction = θ/360 = (12i)/360 = i/30.

You finished the reading!

Lock it in with a few practice questions. This is the last lesson in the chapter.

Last lesson