Answer:
Magnitude of C=

Angle=arctan(Ay+By/Ax+Bx)
Step-by-step explanation:
Let
A = Axi + Ayj
B = Bxi + Byj
where i and j are unit vectors in the direction of x and y axes respectively.
C=A+B
C = (Ax + Bx)i + (Ay + By)j
The magnitude of vector C can be calculated by adding the square of magnitude of its componets and then taking sqaure root.
Magnitude of C=

And the angle will be
Angle=arctan(Ay+By/Ax+Bx)