If the accelerometer measures a total acceleration of 12 m/s^2 and an acceleration of -9 m/s^2 along the Z-axis, what is the acceleration along the X-axis?

Using the Pythagorean theorem, we can find the acceleration along the X-axis.
Acceleration along the X-axis = √(12^2 – 0^2 – (-9)^2)
                                                    = √99 ≈ 9.95 m/s^2.