Make a proportion.
Area of sector = central angle
Area of circle central angle of entire circle
19 = 5π/12
π r2. 2 π
Solve for r. Start by cross multiplying.
(19) (2 π) = (5π/12) (π r2) Divide both sides by π
(19) (2). = (5/12)(π r2) Multiply both sides by 12/5π
(19) (2) (12) = r2 Take square root of both sides.
5π
r = 5.4
Now let's check it.
If the radius is 5.4, then the area of the entire circle is 5.42 π. or 91.6 m2
Is Area of sector = central angle
Area of circle central angle of entire circle
19 = 5 π /12 ???
91.6 2π
38 π = 91.6. (5 π /12)
38 π. = 38 π. YES!!