When vector a is added to vector b, the resultant is vector r such that r = a b. This resultant vector has components rx = ax bx and ry = ay by. How do you determine the magnitude of r?
a. Magnitude of r = √(rx² + ry²)
b. Magnitude of r = ax + bx + ay + by
c. Magnitude of r = ax bx ay by
d. Magnitude of r = ax - bx - ay - by