The heights h (in inches) of two pistons 1 and 2 in an automobile can be modeled by, h₁ = 3.75 sin (726t) + 7.2 and h₂ = 3.75 sin (729( t + 4π/3 ) + 7.2
where t is measured in seconds.
a. How often are these pistons at the same height?