Three equal-length straight rods, of aluminum, Invar, and steel, all at 20.0C, form an equilateral triangle with

Question:

Three equal-length straight rods, of aluminum, Invar, and steel, all at 20.0C, form an equilateral triangle with hinge pins at the vertices. At what temperature will the angle opposite the Invar rod be 59.95o? See Appendix E for needed trigonometric formulas and Table 18-2 for needed data.