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Bunuel

In the figure, the circles with centers A and B are tangent to each other at C, and are tangents to the lines k and m at D and F respectively. If the radius of each circle is √2 and k is
parallel to m, what is the length of EF?

(A) 2√2 + 1
(B) 2√2 + 2
(C) 2√2 + 3
(D) 3√2
(E) 3√2 + 1


Attachment:
2017-11-21_1032_003.png


Bunuel , could you help to understand how the triangle is isoscelece

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m1033512

Draw a tangent as shown in the figure.
In triangle CPA
Angle APC=45
Angle ACP=90
Therefore Angle CAP=45

Similarly In triangle BCP, Angle CBP = 45
Hence, Triangle BAP is a 45-45-90 triangle.
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2017-11-21_1032_003.png
2017-11-21_1032_003.png [ 12.42 KiB | Viewed 1946 times ]

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moropa2018
m1033512

Draw a tangent as shown in the figure.
In triangle CPA
Angle APC=45
Angle ACP=90
Therefore Angle CAP=45

Similarly In triangle BCP, Angle CBP = 45
Hence, Triangle BAP is a 45-45-90 triangle.


Hi, a small query, why is angle APC 45, is there any theorem related to tangent, i am missing out on.
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moropa2018
m1033512

Draw a tangent as shown in the figure.
In triangle CPA
Angle APC=45
Angle ACP=90
Therefore Angle CAP=45

Similarly In triangle BCP, Angle CBP = 45
Hence, Triangle BAP is a 45-45-90 triangle.


How did you find the angle is 45?
Can you please help?

If circle is rotated slightly upwards then it will give different triangle. Not isosceles. And i have heard that we can not go by figure to judge the lengths of lines because we can not measure. If we have been given specific lengths then only we can find relations of lines.

Am I missing something here?

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