Development.

The TEXPA instruction applies the following identities:

• e^x+y=e^x e^y and e^nx=(e^x)ⁿ for n integer,
• $\ln(xy)=\ln(x)+\ln(y)$.
  Warning: this identity is only valid module $2i\pi$
• $\sin(x+y)=\sin(x)\cos(y)+\sin(y)\cos(x)$ and $\cos(x+y)=\cos(x)\cos(y)-\sin(x)\sin(y)$