Let the q-exponential function be:
expq(x)=1+∑n≥1xn(1−q)…(1−qn)
If q.xx′=x′x, then we have the q-trigonometric formulas:
cosq(x+x′)=cosq(x)cosq(x′)−sinq(x)sinq(x′)
sinq(x+x′)=sinq(x)cosq(x′)+cosq(x)sinq(x′)
Can we make q-trigonometry with these formulas?