Sir/Madam

In the problem ,Find the value of lambda Such that the line (X-2)/9 = Y-1/(lambda) = (Z+3)/-6 is perpendicular to the plane

3X-Y-2Z=7. (ans Lambda = - 3)(since line is perpendicular to the plane & parallel to its normal).How do we find the equation of the normal to the given Plane?

From Cartesian form ,we have,  if θ is angle between the line and the plane ax + by + cz + d = 0, then

Now, condition for perpendicularity states that,if a given line is perpendicular to the plane, then it is parallel to its normal. 

Therefore,

Consequently, we have

 

Now, the given equation of the line is:

 

 and

equation of the plane is: 3x - y - 2z = 7

As, it is given that line is parallel to plane, therefore, we have 

On putting the respective values of l, m, n, a , b and c in above equation, we get

 

Hope you get it!!

 

 

 

  • 20

Eqn of plane can be writtes as r.(3i -j-2k) = 7, So for plane vector perp to plane n = (3i -j -2k)

Since line is perp to plane, so its (i.e. line's) vector m = 9i +j (lamda) -6k is // to vector n above, so vector m = p.(vector n) , where p  is any scalar no.

so 9i +j (lamda) -6k = p (3i-j-2k) => 3p = 9  (comparing coeff of i, j and k of both vectors we get p =3 and  -p = lamda (which gives lamda = -p ,  but p = -3

So, .lamda = -3

so lamda = -3

  • 6
What are you looking for?