How to Find Arc Length and Sector Area? (+FREE Worksheet!)

Related Topics

• How to Find the Area and Circumference of Circles
• How to Find Equation of a Circle
• How to Find the Center and the Radius of Circles

Step by step guide to find arc length and sector area of circles

• To find a sector of a circle, use this formula: Area of a sector \(=\color{blue}{πr^2 (\frac{θ}{360})}\)
  \(r\) is the radius of the circle and \(θ\) is the central angle of the sector.
• To find the arc of a sector of a circle, use this formula: Arc of a sector \(=\color{blue}{(\frac{θ}{180})πr}\)

Arc Length and Sector Area – Example 1:

Find the length of the arc. Round your answers to the nearest tenth. \((π=3.14), r=24\) \(cm\), \(\theta=60^\circ\)

Solution:

Use this formula: length of a sector \(=\color{blue}{(\frac{θ}{180})πr}\)
length of a sector \(=(\frac{θ}{180})πr\) \(=(\frac{60}{180})π(24)=(\frac{1}{3})π(24)=8×3.14 \cong 25.1 \) \(cm\)

Arc Length and Sector Area – Example 2:

Find the area of the sector. \((π=3.14\)), \(r=6\) \(ft\), \(\theta=90^\circ\)

Solution:

Use this formula: Area of a sector \(=\color{blue}{πr^2 (\frac{θ}{360})}\)
Area of a sector \(=πr^2 (\frac{θ}{360})=(3.14)(6^2 )(\frac{90}{360})=(3.14)(36)(\frac{1}{4})=28.26 \)\(ft^2\)

Arc Length and Sector Area – Example 3:

Find the length of the arc. Round your answers to the nearest tenth. \((π=3.14), r=28\) \(cm\), \(\theta=45^\circ\)

Solution:

Use this formula: length of a sector \(=\color{blue}{(\frac{θ}{180})πr}\)
length of a sector \(=(\frac{θ}{180})πr\) \(=(\frac{45}{180})π(28)=(\frac{1}{4})π(28)=7×3.14 \cong 22\) \(cm\)

Arc Length and Sector Area – Example 4:

Find the area of the sector. \((π=3.14), r=5 \) \(ft\), \(\theta=80^\circ\)

Solution:

Use this formula: Area of a sector \(=\color{blue}{πr^2 (\frac{θ}{360})}\)
Area of a sector \(=πr^2 (\frac{θ}{360})=(3.14)(5^2 )(\frac{80}{360})=(3.14)(25)(\frac{2}{9}) =17.44 \)\(ft^2\)

Exercises for Finding Arc Length and Sector Area

Find the length of each arc. Round your answers to the nearest tenth.

• \(\color{blue}{r = 28 \ cm, \theta = 45^\circ}\)
• \(\color{blue}{r = 15 \ ft, \theta = 95^\circ}\)
• \(\color{blue}{r = 22 \ ft, \theta = 60^\circ}\)
• \(\color{blue}{r = 12 \ m, \theta = 85^\circ}\)

Download Arc Length and Sector Area Worksheet

• \(\color{blue}{22 \ cm}\)
• \(\color{blue}{24.9 \ ft}\)
• \(\color{blue}{23 \ ft}\)
• \(\color{blue}{17.8 \ m}\)