中三Mensuration數學問題

1(a) The circumference of the circle is 2πr = 80πAfter cutting the cone and extend it on the table, the shortest path should be the straight line which join the point A and its virtual conjugate (called it A'). As sector angle = 4π/5 and then AA'= 2*100*sin(2π/5)= 190.211 cm(b) The shortest path should become longer since the sector angle is increased. In fact, On the other hand, imagine that if the cone is very sharp, than the distance needed to round the cone should be very short.