Posted by benjieo on .
In a triangle PQR. Q=8cm , R=6cm . Cosp=1/12.calculatethe value of p

maths 
MathMate,
I think you mean:
In a triangle PQR. q=8cm , r=6cm . Cos(P)=1/12. Calculate the value of p.
where capital letters mean vertices, lowercase letters mean lengths of sides opposite the corresponding vertex.
Use cosine rule:
p²=q²+r²2qr(cos(P))
and solve for p.