(a(i))[1]
Write down the mathematical name of the angle marked $125^\circ$.
(a(ii))[1]
Give the geometrical reason that makes $x=125$.
(b)[3]
Find the value of $y$. Write down the geometrical facts needed to work out $y$.
(c(i))[1]
Write down the geometrical name for the line $CDE$.
(c(ii))[2]
Work out the size of angle $ODB$.
(c(iii))[2]
Work out angle $BDE$. Give the geometrical reason for your solution.
(d)[2]
Find the interior angle of a regular polygon with 15 sides.