Area of a Circle
\(A = \pi\times r^2\)
\(\pi = \frac{22}{7} = 3.14\)
\(r = \text{radius}\)
\(A =\frac{1}{4} \pi\times d^2\)
\(\pi = \frac{22}{7} = 3.14\)
\(d = \text{diameter}\)
Area of a Sector
If \(\theta\) is measured in degrees then:
\(\text{Area of sector} = \frac{\theta}{360^\circ}\times \text{area of circle}\)
\(\text{Area of sector} = \frac{\theta}{360^\circ}\times \pi\times r^2\)
If \(\theta\) is measured in radians then:
\(\text{Area of sector} = \frac{1}{2}\times r^2 \times \theta\)
\(1 \pi \text { radians} = 180^\circ\)
\(1 \text{ radians ≈ 57.3°}\)