What topic name does this equation go into in physics?

What topic name does this equation go into in physics?

So, I think this equation will go under Types of Physical quantities, Vector Quantities, Magnitude, Direction, etc. under physics & Trigonometry under Mathematics.This formula is used when we need to find the 'x' component of the vector. You need to know basic trigonometry to solve these type of equations & also how to convert between magnitude & angles.

Distance^2= yellow line ^2 (see picture) = 30^2 + 49^2so distance = squareroot of (300^2 +49^2)i dont know if this is how to solve it, but i cnt think of another way