I am working on my math homework, it is due soon and there are no tutoring hours available between now and then.

Write the standard equation for the circle centered at (-3,9) which passes through the origin.

HINT: Every point on the circle is the exact same distance from the circle's center.

I have:

(x+3)^2 + (y-9)^2 = r^2

The hint is throwing me. But it really is just explaining what a radius is, correct?

Seems like I can only work it out if I assume that lineCD is perpendicular to lineAB. I'm not sure I need to know that they're congruent, so maybe it's a typo?

Is there a way to get my TI-84 to not draw the whole line in a graph? For example, if I want to graph a piece work function like f(×) = x+1 for x<2 and x-7 for x>2 can I get it to draw that to easily visualize it, or do I just have to have it draw both full graphs? It would be so much easier for me to see if I could get it to cut off where it needs to.

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