A paper has a base diameter of 8cm and height 3cm (a) use pythagoras theorem to calculate its slant height (b) if the cone is cut and opened out into the sector of a circle what is the angle of the sector
radius = 4
slant height = sqrt (3^2 + 4^2) which we all know is 5 , right?
sector
circumference of base = 2 pi * 4 = 8 pi
radius spread out = slant height = 5
circumference of circle of radius 5 = 2 pi * 5 = 10 pi
so
(8 pi / 10 pi) * 360 degrees