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**zaara****Guest**

A circular sector of radius 15cm and angle 160 degrees is bent in such a way that it forms a hollow cone where the straight sides of the sector meet without overlapping.

How do I find the semi-vertical angle of the cone?

Thanks! :-)

**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,588

I made one out of paper and it appears to be about 22 degrees or half of a 45.

The whole angle appears to be about 45 degrees. I assume you want half of that.

**igloo** **myrtilles** **fourmis**

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**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,588

26.3878 degrees

**igloo** **myrtilles** **fourmis**

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**John E. Franklin****Member**- Registered: 2005-08-29
- Posts: 3,588

I suggest making one out of paper and labelling highlighting the dimensions that

you know or can derive. This experiment will be very fun. If you don't have

a protractor, you can use a watch or clock and the 160 degrees is approximately

from 3.333333 minutes to 30 minutes using the arc of a minute hand.

**igloo** **myrtilles** **fourmis**

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