You're adding the magnitudes of the component forces. This gives an answer that is too large, because the component forces aren't pulling in the same direction as each other. The component forces, $\vec{A}$ and $\vec{B}$, say, need to be added as vectors, that is represented as arrows of length proportional to the magnitude of the components and pointing in the direction of these components. Arrange them tail of $\vec{B}$ to head of $\vec{A}$ and the resultant force (the vector sum of $\vec{A}$ and $\vec{B}$) os represented by an arrow going from the tail of $\vec{A}$ to head of $\vec{B}$.
You can do this using a diagram drawn to scale, or a sketched diagram to which you apply trigonometry. When you've done this sort of thing two or three times you don't even need a sketched vector diagram!