The area of a quarter circle is 19.625 square kilometers. what is the quarter circle's perimeter?

a quarter of a circle is 19.625

so the area of full circle is 19.625 x 4 = 78.5 sq. km

area of a circle is PI x r^2

78.5 = 3.14 x r^2

78.5/3.14 = 25 = r^2

r = sqrt (25) = 5

radius is 5 km

circumference (perimeter) = 2 x PI x r

2 x 3.14 x 5 = 31.4 km

perimeter is 31.4 km