The Compton shift is equal to the Compton wavelength at which angle?

The Compton shift is equal to the Compton wavelength at which angle?

کامپٹن شفٹ کس زاویہ پر کامپٹن طول موج کے برابر ہے؟
Explanation

The Compton shift is equal to the Compton wavelength at a scattering angle of 180 degrees.