In a pentagon, two angles are 40o and 60o, and the rest are in the ratio 1 : 3 : 7. Find the biggest angle of the pentagon.
In a pentagon, two angles are 40o and 60o
∴ Sum of remaining 3 angles =3×180o=540o−40o−60o=540o−100o=440o
Ratio in these 3 angles = 1 : 3 : 7
Sum of ratios = 1 + 3 + 7 = 11
∴ Biggest angle =440o×711=280o