Final answer:
The magnitude of a vector is calculated using the Pythagorean theorem, given the x-component and the angle between the vector and x-axis.
Step-by-step explanation:
To calculate the magnitude of a vector in a 2-dimensional Cartesian system when the x-component and the angle between the vector and the x-axis are known, we use the Pythagorean theorem. Assuming the vector is represented as A and the x-component is Ax, if the angle is θ, then the y-component Ay can be found using the sine function: Ay = A sin(θ). Once Ax and Ay are known, the magnitude A of the vector can be found by the equation A = √(Ax2 + Ay2).