what is the equation of a semi circle with:

-diameter of 6

-amplitude of 3

-starting at the x-axis

-the center is at (5,0)

and what is the generic equation of a semi circle?

thank you

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- Sep 22nd 2008, 04:13 PMarturdo968equation of semi circle
what is the equation of a semi circle with:

-diameter of 6

-amplitude of 3

-starting at the x-axis

-the center is at (5,0)

and what is the generic equation of a semi circle?

thank you - Sep 22nd 2008, 04:30 PM11rdc11
Put your info into the standard equation of a circle

$\displaystyle \frac{(x-5)^2}{9} + \frac{y^2}{9} =1$

and then solve for y and that will give you the equation to a semi circle

$\displaystyle y = \pm \sqrt{9-(x-5)^2}$ - Sep 22nd 2008, 04:34 PMarturdo968
what is the first formula that you showed? i'm not familiar with it

- Sep 22nd 2008, 04:41 PM11rdc11
$\displaystyle (x-a)^2 + (y-b)^2 = r^2$

a and being your center points respectively (5,0) - Sep 22nd 2008, 04:50 PMarturdo968
oh ok i see it now. sorry, thank you very much though, that helped me out. do you by anychance know how to set restrictions on lines so that it only graphs a segment?

- Sep 22nd 2008, 05:23 PM11rdc11
Nope but when you find out let me know to please. Still haven't figured out how to do it on my TI89

- Sep 22nd 2008, 05:30 PMarturdo968
that's exactly what i'm trying to figure out. i'm trying to find the way to set up a domain and range on it and i still can't lol. i'll make sure to tell you if i find something. this is for a project due thursday =p

- Sep 23rd 2008, 09:01 AMbkarpuz
In parametric form, you may let $\displaystyle \cos(t)=\frac{x-5}{3}$ and $\displaystyle \sin(t)=\frac{y}{3}$ to get $\displaystyle \alpha(t)=(x(t),y(t))=(3\cos(t)+5,\sin(t))$ for $\displaystyle t\in[0,\pi]$.