Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2006-02-22 04:26:06

zaara
Guest

sector

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! :-)

#2 2006-02-22 12:18:46

John E. Franklin
Star Member

Offline

Re: sector

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.

Imagine for a moment that even an earthworm may possess a love of self and a love of others.

#3 2006-02-22 12:24:32

John E. Franklin
Star Member

Offline

Re: sector

26.3878 degrees

Imagine for a moment that even an earthworm may possess a love of self and a love of others.

#4 2006-02-22 12:45:37

John E. Franklin
Star Member

Offline

Re: sector

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.

Imagine for a moment that even an earthworm may possess a love of self and a love of others.