Dams dividing an island and quadrilaterals dividing the plane using Euler's formula

[native3]

Q 1. On a circular island we build n straight dams going from
Sea to sea, so the ever two intersect but no three go through
the same point. Use Euler’s Formula to determine how many

Q 2. Into how many parts do two quadrilaterals divide the plane, If
(a) They are convex
(b) They are not necessarily convex

Need help very urgently in solving the above two questions...

Thanks in advance

Please help as soon as possible...

 

[Ray Vickson]

Q 1. On a circular island we build n straight dams going from
Sea to sea, so the ever two intersect but no three go through
the same point. Use Euler’s Formula to determine how many

Q 2. Into how many parts do two quadrilaterals divide the plane, If
(a) They are convex
(b) They are not necessarily convex

Need help very urgently in solving the above two questions...

Thanks in advance

Please help as soon as possible...

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RGV