question_answer

If the focus of parabola  \[{{(y-k)}^{2}}=4(x-h)\]always lies between the lines \[x+y=1\]and \[x+y=3\]then

A) \[0<h+k<2\]    

B) \[0<h+k<1\]

C) \[1<h+k<2\]                

D) \[1<h+k<3\]

Correct Answer: A

Solution :

coordinate of focus will be (h+1,k) now focus  should lie to the opposite side of origin with respect to line \[x+y-3=0\]

Hence h + k>0 and h + k<2.