what is the angle in a triangle when opposite is 4cm and adjacent is 7cm

Well if you are talking about a right angles triangle then

it will be inverse tan or arc tan 

atan(4/7)

$$\underset{\,\,\,\,^{\textcolor[rgb]{0.66,0.66,0.66}{360^\circ}}}{{tan}}^{\!\!\mathtt{-1}}{\left({\frac{{\mathtt{4}}}{{\mathtt{7}}}}\right)} = {\mathtt{29.744\: \!881\: \!296\: \!942^{\circ}}}$$