63.If P(0,1,2) , Q(4, -2, 1) and R(0,0,0) are three points , then angle PRQ is = ?

63.If P(0,1,2) , Q(4, -2, 1) and R(0,0,0) are three points , then angl

1.	63.If P(0,1,2) , Q(4, -2, 1) and R(0,0,0) are three points , then angle PRQ is = ?
Answer» 63.If P(0,1,2) , Q(4, -2, 1) and R(0,0,0) are three points , then angle PRQ is = ?