As we know that angle of semi circle is 180°.
Here,
FLG = 40°
GLH = ?
HLJ = 60°
FLG + GLH + HLG = 180°
40° + GLH + 60° = 180°
GLH + 100° = 180°
GLH = 180° - 100°
GLH = 80°
Now,
FLH = 40° + 80° = 120°
[tex] \sf \: Length \: of \: an \: arc \: of \: GHF = \dfrac{ \theta}{360} \times 2 \pi \: r[/tex]
[tex] = \dfrac {120}{360} \times 2 \times \dfrac{22}{7} \times r[/tex]
[tex] = \frac{1}{3} \times \frac{44}{7} \times r[/tex]
[tex] = \frac{44}{21} \times r[/tex]
[tex] = 2.09r[/tex]
