1. A circle centered at A with radius 10 is externally tangent to a circle centered at B with radius 7. A line that is externally tangent to both circles intersects line AB at C. Find the length BC.

3.

Guest Mar 13, 2020

#3**-2 **

1. By similar triangles, BC = 13*10/7 = 130/7.

3. By similar triangles, YZ = 14^2/8 = 49/2.

Guest Mar 13, 2020

#4**+3 **

**1) ** A circle centered at A with radius 10 is externally tangent to a circle centered at B with radius 7. A line that is externally tangent to both circles intersects line AB at C. Find the length BC.

*BC = 39.66666672 *

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**2)*** AB = 2 x = 1 CD = 4.5 y = 2.25 *

* r = sqrt ( xy ) = sqrt ( 1 * 2.25 ) = 1.5 *

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**3)** XY = 14 WX = 8

*tan(Y) = 8 / 14 ∠Y = 29.7448813°*

*XZ = tan(Y) * WX = 4.571428571*

*YZ = XY - XZ = 9.428571429*

*YZ ≈ 9.428 *

Dragan Mar 13, 2020

#5**+1 **

Question 3

The guest here https://web2.0calc.com/questions/help-asap_85440

Says that Dragan's answer is incorrect.

So I graphed it to scale.

I got the same answer as Dragan. (they are both approximate)

*Although Dragan has not used universal logic.

He has looked at the specific case where WY is a diameter of the circle.

And then he has assumed that it will be the same in all other cases as well.

https://www.geogebra.org/classic/avx3arkb

Melody Oct 10, 2020