2) Area of SECTOR = (ФR²)/2
1st Area of sector OBC= (37° x OB²)/2 = 18.5 x 25 = 462.5 units²
2nd Area of sector OAD= (37° x OA²)/2 = 18.5 x 4 = 74 units²
3th Shaded area = Area of sector OBC - Area of sector OAD = 388.5 units²
4th ARC LENGTH = (Ф x π) x R/180° (this formula is valid for Ф in degrees)
Length of ARC BC=(37° x π) x 5/180 = 37π/36 =3.23
5th Length of ARC AD=(37° x π) x 2/180 = 39π/90 =1.29
6th Scale: ARC AD to ARC BC = 1.29/3.23 =0.399 ≈ 0.40 =2/5
