# A few circle theorem questions (having a bit of trouble)

• Aug 9th 2010, 12:23 AM
jgv115
A few circle theorem questions (having a bit of trouble)
I have a sheet of questions on circle theorems. I did most of them but some of them I don't know what to do.

I know the basic rules:

1) The angle at the centre of the circle is double the angle at the circumference standing on the same arc
2) The angle in a semicircle is right angle or 90 degrees
3) Angles at the circumference of the circle standing on thee same arc are equal
4) The opposite angles of a cyclic quadrilateral are supplementary.

I haven't got up to tangent and chords yet. Just these for now.

http://i22.photobucket.com/albums/b319/jgv115/001.jpg

• Aug 9th 2010, 01:29 AM
sa-ri-ga-ma
In some diagrams, whether the arrow marked lines are parallel?
• Aug 9th 2010, 01:34 AM
jgv115
Umm.. Sorry, I didn't really understand that post :(
• Aug 9th 2010, 01:54 AM
sa-ri-ga-ma
Quote:

Originally Posted by jgv115
Umm.. Sorry, I didn't really understand that post :(

In the figure 8 and 14, two lines are arrow marked. Are they parallel?
• Aug 9th 2010, 02:09 AM
jgv115
Yes!