Question

Why did they use tan instead of sin to find the angle? Tan is opposite over adjacent and we are given opposite and hypotenuse. So we shouldn't be able to use tan right?

Answer 1

That's true.

But first make sure that the given sides are opposite and hypotenuse or other. Because if given two sides of right triangle are perpendicular to each other, then none of the these two sides can be hypotenuse. Because hypotenuse is always opposite to the right angle.

if opposite and hypotenuse are given, we should use sine. Because, sin (angle) = Opposite side / hypotenuse.

But using Pythagoras theorem, we can find the remaining third side and then use tangent of the angle.