Find the angle between the following pair of lines:  -&

Subject

Mathematics

Class

CBSE Class 12

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Sample Papers

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 Multiple Choice QuestionsLong Answer Type

21.

Using elementary transformations, find the inverse of the matrx

 1 3  - 2- 3      0  - 121      0 


22.

Show that of all the rectangles inscribed in a given fixed circle, the square has the maximum area.


23.

Evaluate:  5 x + 3 x2 + 4 x + 10 dx


24.

Evaluate:  2x  x2 + 1   x2 + 3  dx


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25.

Solve the following differential equation:

ex tan y dx + ( 1 - e) sec2 y dy  = 0


26.

Solve the following differential equation:

cos2 x dydx + y = tan x


27.

Find a unit vector perpendicular to each of the vector  a + b   and   a - b , where

  a = 3 i^ + 2 j^ + 2 k^   and    b =  i^ + 2 j^ - 2 k^.


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28.

Find the angle between the following pair of lines:  

- x + 2- 2 = y - 17 = z + 3- 3   and   x + 2- 1 = 2 y - 84 = z - 54

And check whether the lines are parallel or perpendicular.


Let  b1  and   b2  be the two vector parallel to the pair to lines,- x + 2- 2 = y - 17 = z + 3- 3    and    x + 2- 1 = 2 y - 84 = z - 54, respectively.Now,  - x + 2- 2 = y - 17 = z + 3- 3  x - 2 2 = y - 17 = z + 3- 3 x + 2- 1 = 2 y - 84 = z - 54 x + 2- 1 =  y - 42 = z - 54

 b1  =  2 i^ + 7 j^ - 3 k^   and     b2  =  - i^ + 2 j^ + 4 k^  b1  =   2 2 +  7 2 +  - 3 2 =  62  b2  =   - 1 2 +  2 2 +   4  2 =  21b1 . b2  =   2 i^ + 7 j^ - 3 k^  . - i^ + 2 j^ + 4 k^              = 2 ( - 1 ) + 7 x 2 + ( - 3 ) . 4

           = - 2 + 14 - 12

           = 0

The angle  θ  between the given pair of lines is given by the relation,

cos θ =  b1 . b2 b1   b2    cos θ = 0 62 x  21 = 0 θ = cos-1 ( 0 ) = π2

Thus, the given lines are perpendicular to each other and the angle

between them is 900.


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29.

Probabilities of solving problem independently by A and B are 12 and 13respectively. If both try to solve the problem independently, find the probability that

(i) the problem is solved

(ii) exactly one of them solves the problem.


30.

Using integration find the area of the triangular region whose sides have equations  y=2x+1,  y=3x+1  and  x=4.


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