Sample Activity

So, by symmetry, triangle ABC is isosceles So ÐBCD = ÐACE and ÐBCD = 70º Now, fix B and C, and consider other cases Then the line through O and C bisects AB
So ÐBCD = ÐBAC Now ÐABC = ÐBCD since alternate angles are equal If ÐCAB = 70º then ÐABC = 70º and ÐACB = 40º
Since angles in the same segment are equal it is always true that
Now ÐABC = ÐBCD since corresponding angles are equal Consider the case where AB is parallel to CD Therefore

Place the cells in a correct logical order to form a proof of the alternate segment theorem.
'X' marks the centre of a circle