Answer:
Here, we will use the formula from trigonometry which defines a radian
we know that an angle is a radian when the length of the radius of the circle is equal to the length of the arc formed
hence, if the radius is r and the arc is r, the angle (in radians) will be 1
if the radius is r and the arc is 2r, the angle in radians will be equal to:
length of arc / radius = 2r/r = 2 radians
I believe this will explain what is actually happening in these type of questions
So, the equation:
Θ(in radians) = s / r (where the length of arc is s and the radius is r)
π/4 = s / 12
s = 3π or 9.42 inches
