Question

In the circle below with center O, diamter AC, and AB=BC, find the value of x+y

Answer 1

The diagram can be found here: http://tinyurl.com/43oq72n
It's problem #13.
I know y = 45, but I don't know how to get the value of x. Is there a circle theorem I'm missing or do I find remote interior angles?

Answer 2

are u sure of your url ? can't see the diagram

Answer 3

I'm sure, it's a Google Books link. The problem is found in Gruber's Complete Preparation for the New SAT. Try copying the problem I wrote and pasting it into Google. The first result should be just that.

Answer 4

sorry, not working...

Answer 5

Oh wait, try Googling "a horizontal line has a length of 100 yards. a vertical line is drawn at one of its ends. if lines are drawn every ten yards thereafter, until the ither end if reached, how many vertical lines are finally drawn?"
NOW it should be the first result. The problem above is on the same page as the problem I had posted.

Answer 6

tinyurl just a link to publication, googling as suggested doesn't bring it up.

Just draw it (paint accessory).

Answer 7

thanks estudier, i was beginning to think it was my fault.

Answer 8

Ok, I'll try drawing it on paint.

Answer 9

Nah, I'll just attach the file.

Answer 10

okay, did you see that the little triangle CO(something) has two sides that are the same length ?

Answer 11

Nah, I'll just attach the file.

Answer 12

Yup, I do. They're congruent.

Answer 13

But where do I go from there? The side next to the 40 degree angle is also 40 degrees.

Answer 14

Call, the unlabelled point D and OD = DC

Construct OB

Follow your nose.

Answer 15

well you can know what is DOC angle, right ? see what's come next ?

Answer 16

Nah, I'll just attach the file.

Answer 17

Ok, I see it now. Draw shapes to help you with the problem. Thanks for all the help (and persistence) guys!

Answer 18

So the part I got stuck on was forgetting to figure out the third side of the smaller angle, even when I knew both sides. Haha, wow. Thanks again, guys.

Answer 19

and girls :p