Bigger circle.

[JulianMathHelp]

In the following site, https://mabrymsblog.typepad.com/mrs_albertson/Bigger Circle answers.pdf

It says given the following information solve. Am I allowed to say BD is the diameter right away because it looks like it? Or is it assuming, and I have to prove it.

 

[Dr.Peterson]

Since BD is a chord passing through O, which you are told is the center (by calling it Circle O), you can be certain that BD is a diameter. There is no unsupported assumption needed.

 

[JulianMathHelp]

Since BD is a chord passing through O, which you are told is the center (by calling it Circle O), you can be certain that BD is a diameter. There is no unsupported assumption needed.

But how do we know BD is a chord? It might not be a straight line right?

 

[lev888]

But how do we know BD is a chord? It might not be a straight line right?

If it was not a straight line the problem would not refer to angle CDB.

 

[JulianMathHelp]

Yeah, I saw the angles too after so that made sense.