Solving Vector Components and Theta with Pythagorean Theorem

[ColinTI89]

Homework Statement

Vector A= 5.00 m (See the attached image for the graphical representation)
Vector B=17.0m
Vector C=15.0 m

Homework Equations

Pythagorean Theorem, Basic trigonometry

The Attempt at a Solution

Finding the magnitude of the resultant vector is not where I'm having issues. I just can't figure out how to find theta (the angle of depression of the resultant vector). The only thing I could think of is to set up the X and Y components of the vector, but I don't know the lengths of those so I can't get any futher than that to calculate the angle.

Thanks in Advance,
Colin

 

[cupid.callin]

i'm bad with geometry so i can only tell you that find each vector in form of: x\hat{i} + y\hat{j}

find net of all vectors

then angle with horizontal is: tan\theta = \frac{y}{x}