Question regarding compton scattering:

a photon with wavelength = 0.1385 nm scatters from an electron that is initially at rest. what must be the angle between the direction of propagation of the incident and scattered photons if the speed of the electron immediately after the collision is 8.90*10^6 m/s?

The scalar triple product computes the magnitude m of the moment of a force vector f about a specified line. it is m = (r × f) · n, where r is the position vector from the line to the point of application of the force and n is a unit vector in the direction of the line. use matlab to compute the magnitude m for the case where f = [12, −5, 4] n, r = [−3, 5, 2] m, and n = [6, 5, −7].