Hi there!
• A = 70 m²
• ϴ = 170° = [tex]\dfrac {17\pi}{18}[/tex] rad.
According to th' question :-
Area of Sector = [tex]\dfrac {1}{2}[/tex]r².ϴ
70 m² = [tex]\dfrac {1}{2}[/tex]r². [tex]\dfrac {17\pi}{18}[/tex]
r² = [tex]\dfrac {36.70}{17\pi}[/tex] m²
r ≈ [tex]\sqrt {47. 18476}[/tex] m
r ≈ 6.9 m
Hence,
Th' radius of circle, r = 6.9 m
~ Hope it helps!