# circle geometry help 4

#### spruancejr

What do you specifically do not understand?

#### andy69

What do you specifically do not understand?
i have trouble giving the reasons in circle geometry can you or somebody else help me.its just question 3d

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#### sa-ri-ga-ma

i have trouble giving the reasons in circle geometry can you or somebody else help me.its just question 3d
When the two chords Ab and CD intersect each other at E, they satisfy the following condition.

$$\displaystyle \frac{AE}{EB} = \frac{CE}{ED}$$ .............(1)

AE = 4, AB = 7. So EB = ...?

CD = l, ED = x, so CE = ...?

Substitute these values in equation (1) and simplify.

The equation obtained is

$$\displaystyle x^2 - lx + 12 = 0.$$ Or

$$\displaystyle l = x + \frac{12}{x}$$

To get the minimum length of the chord CD, find dl/dx and equate it to zero. Then solve for x. Substitute this value in eq.(1) to find CF, then find CD.

#### andy69

When the two chords Ab and CD intersect each other at E, they satisfy the following condition.

$$\displaystyle \frac{AE}{EB} = \frac{CE}{ED}$$ .............(1)

AE = 4, AB = 7. So EB = ...?

CD = l, ED = x, so CE = ...?

Substitute these values in equation (1) and simplify.

The equation obtained is

$$\displaystyle x^2 - lx + 12 = 0.$$ Or

$$\displaystyle l = x + \frac{12}{x}$$

To get the minimum length of the chord CD, find dl/dx and equate it to zero. Then solve for x. Substitute this value in eq.(1) to find CF, then find CD.
im really sorry about this but im not sure what to do im not very good at circle geometry because my teacher was absent for most of this whole topic and know i have a test about it, again im really sorry can you explain it abit more.

#### sa-ri-ga-ma

im really sorry about this but im not sure what to do im not very good at circle geometry because my teacher was absent for most of this whole topic and know i have a test about it, again im really sorry can you explain it abit more.
Open any text book and find the properties of the circle. For that there is no need of any teacher.

#### andy69

When the two chords Ab and CD intersect each other at E, they satisfy the following condition.

$$\displaystyle \frac{AE}{EB} = \frac{CE}{ED}$$ .............(1)

AE = 4, AB = 7. So EB = ...?

CD = l, ED = x, so CE = ...?

Substitute these values in equation (1) and simplify.

The equation obtained is

$$\displaystyle x^2 - lx + 12 = 0.$$ Or

$$\displaystyle l = x + \frac{12}{x}$$

To get the minimum length of the chord CD, find dl/dx and equate it to zero. Then solve for x. Substitute this value in eq.(1) to find CF, then find CD.
EB=3 how can you get CE when theres 2 unknowns the fraction would just be 4/3=CE/X

#### sa-ri-ga-ma

EB=3 how can you get CE when theres 2 unknowns the fraction would just be 4/3=CE/X
CE = CD - ED = (l - x)

#### andy69

CE = CD - ED = (l - x)
ok so 4/3=(l-x)/x
cross multiply
4x=3(l-x)
4x=3l-3x
4x+3x=3l
7x=3l
x=3l/7

now do i sub this answer into the 2nd equation that you said

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#### Wilmer

now do i sub this answer into the 2nd equation that you said
I think it's time you be told that you need classroom help;
we can't replace your teacher here...