Circle: Area and Perimeter

Area and Sector

 

 

Circle

 

Parts of A Circle

Rendered by QuickLaTeX.com


Area of A Circle

 

Rendered by QuickLaTeX.com

\(A = \pi\times r^2\)

\(\pi = \dfrac{22}{7} = 3.14\)

Rendered by QuickLaTeX.com

\(A =\dfrac{1}{4} \pi\times d^2\)

\(\pi = \dfrac{22}{7} = 3.14\)


Area of A Sector

 

Rendered by QuickLaTeX.com

\(\text{Area of sector} = \dfrac{1}{2}\times r^2 \times \theta\)

\(\theta\) in radian

 

\(\text{Area of sector} = \dfrac{\theta}{360^\circ}\times \pi\times r^2\)

\(\theta\) in degree


Circumference of A Circle

 

Rendered by QuickLaTeX.com

 

\(\text{circumference of circle} = 2\times \pi\times r\)

\(\pi = \frac{22}{7} = 3.14\)

\(r = \text{radius}\)

Rendered by QuickLaTeX.com

 

\(\text{circumference of circle} =\pi\times d\)

\(d = \text{diameter}\)

Arc Length

 

Rendered by QuickLaTeX.com

 

\(\text{If θ is measured in degrees then:}\)

\(\text{Arc length} = \frac{\theta}{360^\circ} \times \text{circumference of circle} \)

\(\text{Arc length} = \frac{\theta}{360^\circ} \times 2\times \pi \times r \)

 

\(\text{If θ is measured in radians then:}\)

\(\text{Arc length} = \theta \times r\)

 

\(1 \pi \text { radians} = 180^\circ\)

\(1 \text{ radians ≈  57.3°}\)

 

Exercise

--- Open this page ---

(Next Lesson) Perimeter and Arc Length
Kembali ke Circle: Area and Perimeter