12th Class Mathematics Sample Paper Mathematics Sample Paper-8

  • question_answer
    Find the distance from the point (3, 4, 5) to the point, where the line \[\frac{x-3}{1}=\frac{y-4}{2}=\frac{z-5}{2}\] meets the plane \[x+y+z=2.\]

    Answer:

    Given equation of plane is\[x+y+z=2\]          ?(i) Equation of the line is             \[\frac{x-3}{1}=\frac{y-4}{2}=\frac{z-5}{2}=\lambda \,\,(say)\]     ?(ii) Then, any point P on the line is \[P(\lambda +3,\,\,2\lambda +4,\,\,2\lambda +5)\]                                    ?(iii)             Since, the point P lies on the given plane. So, it will satisfies the plane. \[\therefore \]      \[(\lambda +3)+(2\lambda +4)+(2\lambda +5)=2\] \[\Rightarrow \]   \[5\lambda +12=2\] \[\Rightarrow \]   \[5\lambda =-\,10\] \[\Rightarrow \]   \[\lambda =-\,2\] On putting the value of \[\lambda \] in Eq. (iii), we get Coordinates of \[P=(-\,2+3,\,\,-\,4+4,\,\,-\,4+5)=(1,\,\,0,\,\,1)\] Now, the distance between P(1, 0, 1) and (3, 4, 5) is             \[|PQ|\,=\sqrt{{{(3-1)}^{2}}+{{(4-0)}^{2}}+{{(5-1)}^{2}}}\] \[[\because d=\sqrt{{{({{x}_{2}}-{{x}_{1}})}^{2}}+{{({{y}_{2}}-{{y}_{1}})}^{2}}+{{({{z}_{2}}-{{z}_{1}})}^{2}}}]\]             \[=\sqrt{{{(2)}^{2}}+{{(4)}^{2}}+{{(4)}^{2}}}=\sqrt{4+16+16}\]             \[=\sqrt{36}=6\,\,\text{units}\]


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