Trigonometry problem

Question

the area of a sector of a circle with a central angle of a 2/5 pie rad is 20m^2. Find the radius of the circle

Answer 1

Since your central angle is measured in rads, you can use a simple area of sector formula: K = 1/2r²Θ

1/2r²(2/5π) = 20

r² = 100 / π

r = 10 / √π