The radius of the small round field is increased by 5 m to get the large round field, and the area of the field is increased by 3 times

The radius of the small round field is increased by 5 m to get the large round field, and the area of the field is increased by 3 times

The radius of a small site is 5 m. if the radius of a small site is r, then the area of a small site is π R & # 178; if the area of a large site is π (R + 5) &# 178; if the value of R is 4 π R & # 178; = π (R + 5) &# 178; 4R & # 178; = R & # 178; + 10R + 253r & # 178; - 10r-25 = 0 (3R + 5) (R-5) = 0, then r = 5 or r = - 5 / 3, because