Joe has just completed an evening art course on creating stained glass,
and so decides to create a window for his conservatory. He first designs his
window on paper coming up with small sections that he hopes to piece
together later. Figure 1 shows his first attempt.
(a) AB is parallel to DC, ∠ABE = 25◦ and ∠AEB = 120◦.
(I) Explain how Joe can work out ∠EDC without measuring it.
(ii) Find ∠EAB explaining your reasoning.
(iii) Find a triangle that is similar to triangle ABE explaining your
reasoning. [2]
(iv) If AB = 8cm, AE = 3.9 cm and EC = 9cm, use the similar
triangles you found in part (a)(iii) to find the length of CD.
(v) Given that ∠DBC = 84◦, find ∠ACB, and hence explain whether
or not ABC is an isosceles triangle.
please see my attachment
thanks

Come on what have you tried. What you basically need to know to solve this are:

- When you have two straight lines crossing each other, the opposite angles are equal.
- The total of the interior angles in a triangle is always equal to 180 degrees.
- Similar triangles have the same interior angles and the ratio of their sides are the same.

Can you try it out? :)