Platelets are used for blood clotting
Vitamin K are also for blood clotting
How are they related?

Question

rogue · Answer

Vitamin k allows certain blood clotting proteins to bind to the membranes of platelets. When these proteins complexes assemble together, they can activate one another and begin clot formations.

anonymous · Answer

when the blood is exposed to air or friction with a rough surface the blood platelets form with the destroyed cells a proteinic substance called Thromboplastin (enzyme)....the thromboplastin with the help of vitamin k and calcium ions activates prothrombin which is secreted by the liver to form the active Thrombin  ( vitamin k also helps the liver to secrete prothrombin)