Given that $AB=12$, $CD=1$ and the semicircle is tangent to $BC$, find the radius of semicircle.
$begingroup$
I tried it by reflecting it horizontally, by making complete circle and using it as incircle. But, was not able to get an answer.

geometry euclidean-geometry triangle circle
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$begingroup$
I tried it by reflecting it horizontally, by making complete circle and using it as incircle. But, was not able to get an answer.

geometry euclidean-geometry triangle circle
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Sumit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
I tried it by reflecting it horizontally, by making complete circle and using it as incircle. But, was not able to get an answer.

geometry euclidean-geometry triangle circle
New contributor
Sumit Singh is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
I tried it by reflecting it horizontally, by making complete circle and using it as incircle. But, was not able to get an answer.

geometry euclidean-geometry triangle circle
geometry euclidean-geometry triangle circle
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edited 9 hours ago
user21820
38.9k543153
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asked 16 hours ago
Sumit SinghSumit Singh
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2 Answers
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$begingroup$
Let $K$ be a touching point to $CB$, the radius be equal to $x$ and $O$ be a center of the circle.
Thus, $$CO=x+1,$$
$$AC=2x+1,$$ $$CK=sqrt{(1+x)^2-x^2}=sqrt{2x+1}.$$
Thus, since $Delta CKOsimDelta CAB,$ we obtain:
$$frac{sqrt{2x+1}}{2x+1}=frac{x}{12}.$$
Can you end it now?
I got $x=4$.
$endgroup$
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$begingroup$
We have $$CE^2+r^2=(1+r)^2$$ and $$AB=BE=12$$ and $$12^2+(2r+1)^2=(12+CE)^2$$
Can you solve this system?
$endgroup$
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2 Answers
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active
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2 Answers
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$begingroup$
Let $K$ be a touching point to $CB$, the radius be equal to $x$ and $O$ be a center of the circle.
Thus, $$CO=x+1,$$
$$AC=2x+1,$$ $$CK=sqrt{(1+x)^2-x^2}=sqrt{2x+1}.$$
Thus, since $Delta CKOsimDelta CAB,$ we obtain:
$$frac{sqrt{2x+1}}{2x+1}=frac{x}{12}.$$
Can you end it now?
I got $x=4$.
$endgroup$
add a comment |
$begingroup$
Let $K$ be a touching point to $CB$, the radius be equal to $x$ and $O$ be a center of the circle.
Thus, $$CO=x+1,$$
$$AC=2x+1,$$ $$CK=sqrt{(1+x)^2-x^2}=sqrt{2x+1}.$$
Thus, since $Delta CKOsimDelta CAB,$ we obtain:
$$frac{sqrt{2x+1}}{2x+1}=frac{x}{12}.$$
Can you end it now?
I got $x=4$.
$endgroup$
add a comment |
$begingroup$
Let $K$ be a touching point to $CB$, the radius be equal to $x$ and $O$ be a center of the circle.
Thus, $$CO=x+1,$$
$$AC=2x+1,$$ $$CK=sqrt{(1+x)^2-x^2}=sqrt{2x+1}.$$
Thus, since $Delta CKOsimDelta CAB,$ we obtain:
$$frac{sqrt{2x+1}}{2x+1}=frac{x}{12}.$$
Can you end it now?
I got $x=4$.
$endgroup$
Let $K$ be a touching point to $CB$, the radius be equal to $x$ and $O$ be a center of the circle.
Thus, $$CO=x+1,$$
$$AC=2x+1,$$ $$CK=sqrt{(1+x)^2-x^2}=sqrt{2x+1}.$$
Thus, since $Delta CKOsimDelta CAB,$ we obtain:
$$frac{sqrt{2x+1}}{2x+1}=frac{x}{12}.$$
Can you end it now?
I got $x=4$.
answered 16 hours ago
Michael RozenbergMichael Rozenberg
103k1891195
103k1891195
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add a comment |
$begingroup$
We have $$CE^2+r^2=(1+r)^2$$ and $$AB=BE=12$$ and $$12^2+(2r+1)^2=(12+CE)^2$$
Can you solve this system?
$endgroup$
add a comment |
$begingroup$
We have $$CE^2+r^2=(1+r)^2$$ and $$AB=BE=12$$ and $$12^2+(2r+1)^2=(12+CE)^2$$
Can you solve this system?
$endgroup$
add a comment |
$begingroup$
We have $$CE^2+r^2=(1+r)^2$$ and $$AB=BE=12$$ and $$12^2+(2r+1)^2=(12+CE)^2$$
Can you solve this system?
$endgroup$
We have $$CE^2+r^2=(1+r)^2$$ and $$AB=BE=12$$ and $$12^2+(2r+1)^2=(12+CE)^2$$
Can you solve this system?
answered 15 hours ago
Dr. Sonnhard GraubnerDr. Sonnhard Graubner
75.1k42865
75.1k42865
add a comment |
add a comment |
Sumit Singh is a new contributor. Be nice, and check out our Code of Conduct.
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