Here is a question,
An isosceles triangle is formed with thin rod of length and coefficient of linear expansion as the base and two thin rods each of length and coefficient of linear expansion as the two sides. If the distance between the apex and the midpoint of the base remain unchanged as the temperature is varied, find a relation between , , , .
Here is how I figured a relation,
& in and
Differentiating with respect to T,
We know and
Why am I getting two answers?? Some one please help!