$$cos12.cos24.cos48.cos96$$ Bu ifadeyi $sin12$ ile çarpıp bölelim.
$$=\frac{sin12.cos12.cos24.cos48.cos96}{sin12}$$
$$=\frac{sin24.cos24.cos48.cos96}{2.sin12}$$
$$=\frac{sin48.cos48.cos96}{4.sin12}$$
$$=\frac{sin96.cos96}{8.sin12}$$
$$=\frac{sin192}{16.sin12}$$
$$=\frac{-sin12}{16.sin12}$$
$$=\frac{-1}{16}$$ olur.