Interface:Tau day theorems

This is what one is supposed to prove for the Tau day exercises.

 param (PROPOSITIONAL Interface:Classical_propositional_calculus ) param (FIRSTORDER Interface:First-order_logic_with_quantifiability (PROPOSITIONAL) )

kindbind (object real) var (real x y z θ α)

term (real (+ real real)) term (real (− real real)) term (real (· real real)) term (real (/ real real)) term (real (√ real)) term (real (sin real)) term (real (cos real)) term (real (τ)) term (real (0)) term (real (1)) term (real (2)) term (real (4))

stmt (TauIsPeriodOfSine  ((sin (θ + (τ))) = (sin θ)))

stmt (TauIsPeriodOfSineQuarterTurn   ((sin ((α + ((τ) / (4))) + (τ))) = (sin (α + ((τ) / (4))))) )

stmt (CosinePeriod  ((cos (θ + (τ))) = (cos θ)))

stmt (CosineTau  ((cos (τ)) = (1))) 