If is an acute angle between the lines k x^2-4 x y+y^2=0 and = 1 2 , then value of k is

Step-by-step solution

aligned & = | 2 h^2-a b a+b | & 1 2 = | 2 (-2)^2-k 1 k+1 | & 1 2 = 2 4-k k+1 & (k+1)=4 4-k & k=3 aligned