Answer:
2p-1/p
Step-by-step explanation:
Solution :
Let
be the unit vector in the direction parallel to the plane and let
be the component of F in the direction of
and
be the component normal to
.
Since, 


Therefore, 
From figure,

We know that the direction of
is opposite of the direction of
, so we have



The unit vector in the direction normal to the plane,
has components :


Therefore, 
From figure,

∴ 

Therefore,


Answer: 21 . . . . . .
Credit to the person below-