Answer:
1/4 radian = 45°/π ≈ 14.32°
Explanation:
The area of a sector is given by the formula ...
A = 1/2r²θ . . . . . radius r and central angle θ in radians
Then the angle is ...
θ = 2A/r² . . . . . radians
θ = 2(2 km²)/(4 km)² = 4/16 = 1/4 . . . . radian
The angle measure is 1/4 radian = 45°/π ≈ 14.32°