CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2010

  • question_answer
    If the plane\[3x+y+2z+6=0\]is parallel to the line\[\frac{3x-1}{2b}=3-y=\frac{z-1}{a},\]then the value of \[3a+3b\]is

    A)  \[\frac{1}{2}\]                                  

    B)  \[\frac{3}{2}\]

    C)  \[3\]                    

    D)         \[4\]

    E)  \[\frac{5}{2}\]

    Correct Answer: B

    Solution :

    Comparing the given equation of plane \[3x+y+2z+6=0\]with \[lx+my+nz+d=0\] \[\Rightarrow \] \[l=3,m=1,n=2\] Also, comparing given equation of line                 \[\frac{x-\frac{1}{3}}{\frac{2b}{3}}=3-y=\frac{z-1}{a}\] with\[\frac{x-{{x}_{1}}}{{{a}_{1}}}=\frac{y-{{y}_{1}}}{{{b}_{1}}}=\frac{z-{{z}_{1}}}{{{c}_{1}}},\]we get                 \[{{a}_{1}}=\frac{2b}{3},{{b}_{1}}=-1,{{c}_{1}}=a\] For parallel line                 \[l{{a}_{1}}+m{{b}_{1}}+n{{c}_{1}}=0\] \[\Rightarrow \]               \[3.\frac{2b}{3}+1.(-1)+2a=0\] \[\Rightarrow \]               \[2a+2b=1\] \[\Rightarrow \]               \[a+b=\frac{1}{2}\] \[\Rightarrow \]               \[3a+3b=\frac{3}{2}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner