Final answer:
The fraction used for shrink in a 60 degree bend can be calculated using the formula: Shrink fraction = (Arc length of the bend - Outer circumference of the bend) / Outer circumference of the bend.
Step-by-step explanation:
The fraction used for shrink in a 60 degree bend depends on the material being bent. In general, when a material is bent, it undergoes some amount of deformation, resulting in a change in its dimensions.
This change can be represented by the formula:
Shrink fraction = (Arc length of the bend - Outer circumference of the bend) / Outer circumference of the bend
For example, if the arc length of the bend is 10 cm and the outer circumference of the bend is 30 cm, the shrink fraction would be (10 - 30) / 30 = -0.333.