Circle Theorems

I was recently moved up to top Maths set in school, and I must say, it's a huge jump from what I was doing in the middle set.
Now, today we were doing Circle Theorems, and the only way I could complete my worksheet was to get my friend to help me by running me throguh it, unfortunatley, he's not very good at explaining things so he was basically giving me the answers.
It didn't help that the teacher assumed that we all knew how to do them also, so she just put us straight into it only going through Corresponding Angles and so on beforehand.
I was wondering whether anybody could explain how to do Circle Theorems in a way that a beginner to them could understand.
We were donig the one with a circle and an arrow head shape in the middle, with loads of little angles being formed, and had to use one point named "A" and write a formula for each angle, the formula was basically how to the given other angle.

Would you be able to somehow get the problem on the computer and post it?

I can find an example of one, it isn't just one i'm stuck with though, I have no idea how to do it at all..

Here is one:



And Another:



I have no idea how to work them out.

Is there any saying like AO is perpendicular to BO (That sounds funny!)?

Originally Posted by JordanKnight

I can find an example of one, it isn't just one i'm stuck with though, I have no idea how to do it at all..

Here is one:



And Another:



I have no idea how to work them out.

Ah, this sort of thing.

Well, there are always rules that you need to know to properly solve these. I remember doing them last year but, alas, cannot remember what those rules are.

However, if this is new this year your textbook should have a list of them for you to reference.

It's not exactly new to the rest of my set, me and a few others have just been moved up at the end of the top sets module, which contained these, so the teacher assumed that we all knew them.

Well, all I can say is to ask you friend for a better explanation. Have them go through it step-by-step. If you don't get something, tell them to go over it again.

Wish I was more help, but we only did these as a minor unit and that was a year ago, so all I recall is that there are rules, not what they are. :/

Ok thanks for all of the help, hopefully I can move the Grade B I currently have to an A by taking the higher exam paper .

Don't know if you got help for this or not, but with the first problem, B appears to be an angle embedded in an equilateral triangle, meaning it's 60 degrees, while A appears to cover a third of the circle, meaning that it is 120 degrees. If you imagine the third leg of the triangle, you can reason that the isosceles sub-triangle formed by the legs of A and the imaginary leg has angles of 30 degrees for each of the far corners, again meaning that A = 120 degrees.

For the second, the shape appears to form two adjacent isosceles triangles; the angle farthest from A is equal to A, and the same applies for B. If you know one of them, you can figure out the other.

The reason I say "appears" is because when sides of a figure are congruent to one another, there is usually a small perpendicular dash through the center of them to denote that (or set of dashes if there exists more than one set of congruent sides, as with a rectangle).

I know for definite since I am doing GCSE Maths that the angle at the centre is double of that which is touching the circle. In other words, if "a" was 30 degrees then "b" would be 60 degrees.