Three equal -length straight rods, of aluminium invar and steel all at `20^(@)C`, form an equilateral triangle with hinge pins at the vertices. At what temperature will the angle opposite to the invar rod be `59.95^(@)`?
`alpha_("invar")=0.7xx10^(-6)//C^(@), alpha_("steel")=11xx10^(-6)//C^(@), alpha_("aluminium")=23xx10^(-6)//C^(@)`
