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Mathematics 18 Online
OpenStudy (anonymous):

Help?(: {Find x & y.}

OpenStudy (anonymous):

OpenStudy (anonymous):

i worked it out partly.. and got this as my answer.(: Hope it helps.

OpenStudy (mathstudent55):

|dw:1372785775551:dw|

OpenStudy (anonymous):

k

OpenStudy (mathstudent55):

That gives 5y = 12x

OpenStudy (mathstudent55):

The product of the lengths of the segments of one chord equals the product of the lengths of the segements of the other chord.

OpenStudy (anonymous):

In english please? ..you lost me there.

OpenStudy (mathstudent55):

Now look at right triangle TRV, with right angle R.

OpenStudy (anonymous):

ok

OpenStudy (mathstudent55):

This is a chord. |dw:1372785948886:dw|

OpenStudy (mathstudent55):

Now you have a circle with two intersecting chords. |dw:1372785997147:dw|

OpenStudy (anonymous):

k

OpenStudy (mathstudent55):

One chord has two segments of lengths a and b. The other chord has segments of lengths c and d. |dw:1372786042595:dw|

OpenStudy (mathstudent55):

ok?

OpenStudy (anonymous):

.sure?

OpenStudy (anonymous):

can we plug in the numbers from the problem? cuz im still not getting it..

OpenStudy (mathstudent55):

I'm trying to first explain the reason why you can write the equations. You have two variables, x and y. You need two equations. We're going to use the chords to get one equation. We're going to use the right triangle to get the second equation.

OpenStudy (anonymous):

k

OpenStudy (mathstudent55):

In your problem, one chord has segments of lengths 5 and y. The other chord has segements of lengths 12 and x. That means 12x = 5y This is our first equation.

OpenStudy (mathstudent55):

Now for the second euquation, we use the right triangle TRV with right angle R.

OpenStudy (mathstudent55):

One leg measures 15. One leg measures y. The hypotenuse measures x + 9.

OpenStudy (mathstudent55):

Now we use the Pythagorean Theorem using the lengths of the sides to get our second equation. 15^2 + y^2 = (x + 9)^2

OpenStudy (mathstudent55):

Now we have our two equations. We need to solve them simultaneously for x and y.

OpenStudy (dan815):

that is necessarily not the hypotenuse

OpenStudy (dan815):

does not say SR is passing through the center

OpenStudy (anonymous):

???

OpenStudy (mathstudent55):

@dan815 You are correct.

OpenStudy (dan815):

:)

OpenStudy (anonymous):

So was my answer wrong, or not?

OpenStudy (mathstudent55):

I was thinking SR is a diameter, but it does not state it is anywhere.

OpenStudy (dan815):

yeah i thought so at first too, it would have this a lot simpler

OpenStudy (anonymous):

Soo.....?

OpenStudy (mathstudent55):

That means we need a different method of getting the second equation. The first equation is still good, 12x = 5y. Now let's work on the second equation using the segments of the tangent and secant TQ.

OpenStudy (mathstudent55):

|dw:1372787216311:dw|

OpenStudy (mathstudent55):

The secant is made up of two segments. The external part (outside the circle) and the internal part (inside the circle).

OpenStudy (mathstudent55):

The relaitionship between the lengths of the segments is: (whole secant) * (external segment of the secant) = (tangent)^2

OpenStudy (mathstudent55):

In our problem, the entire secant is 9 + x + 12 = x + 21 The external part of the secant is 9 The tangent is 12

OpenStudy (dan815):

|dw:1372787402387:dw|

OpenStudy (dan815):

doesnt it make you stare at it

OpenStudy (dan815):

theres some crazy symmetry going on in that picture

OpenStudy (anonymous):

Ok im really confused now.. Can i just get a simple yes or no to my question? Was it wrong or not? Ive spent over 20 minutes on this i have to move on to other problems. Thanks for trying guys.

OpenStudy (dan815):

|dw:1372787689525:dw|

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