



 
Hi Amy, I drew a picture of the cone as I see it
Triangle ABC is a right triangle and hence Pythagoras' theorem tell us
so
Hence when the cone is slit and rolled out it is a sector of a circle of radius 3.39 inches.
The length of the arc RQ is the circumference of the circle at the base of the cone. This circle has a radius of 0.5 inches and the circumference of a circle is 2 r and hence the length of the arc RQ is inches. What remains is to find the measure of the angle RPQ. The circumference of the circle containing the arc RQ is
The length of arc RQ is only a fraction of this length, in fact the fraction is /20.67 and hence the angle RPQ is the same fraction of 360 degrees. Thus the measure of the angle RPQ is
I hope this helps,  


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