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Assertion (A) : If a line make angles 45...

Assertion (A) : If a line make angles `45^(@), 45^(@)` with the x and y axis repectively then it makes angle `60^(@)` with z - axis
Reason (R ) : If `alpha,beta,lambda` are the angle made by a line with the coordinate axes then `cos^(2) alpha + cos^(2)beta + cos^(2) lambda = 1`

A

Both A and R are ture and R is the correct explanation of A

B

Both A and R are true but R is the correct explanation of A

C

A is true but R is false

D

A is false but R is true

Text Solution

Verified by Experts

The correct Answer is:
D
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AAKASH SERIES-DIRECTION COSINES & RATIOS-PRACTICE EXERCISE
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  2. If (1,2,-2) are the D.R's of a line then Statement-I : The D.C's of t...

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  3. Assertion (A) : If a line make angles 45^(@), 45^(@) with the x and y ...

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  4. If a line makes angles cos^(-1)(1//5),cos^(-1)(3//5) with X and Y- axe...

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  5. The angle between the two lines whose direction cosines are ((sqrt(3))...

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  6. The angle between the line passing through the points (3,1,-2) and (4...

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  7. If the d.r's of two lines are (x,3,5) and (2,-1,2) and if the anlgle ...

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  8. The d.r.s of two perpendicular lines are 1,-3,5 and lambda,1 + lambda...

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  9. If the line joining the points (-1,2,3) (2,-1,4) is perpendicular to t...

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  10. If (1,-2,-2) and (0,2,1) are direction ratios of two lines, then direc...

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  11. If the line joining the points (1,4,2) and (-2,1,2) is inclined at an...

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  12. If the d.r's of bar(OA),bar(OB) are (1,-2,3),(-3,4,5) then the d.c's ...

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  13. If (l(1),m(1),n(1)),(l(2),m(2),n(2)) are d.c's of two lines then find ...

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  14. If the d.c's of the two lines are (2)/(3),(2)/(3),(1)/(3),(5)/(13),(12...

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  15. If (6,-2,-3),(1,2,2) are d.r's of two lines then the d.c's of line bis...

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  16. If (l(1),m(1),n(1)),(l(2),m(2),n(2)) are direction cosines of two line...

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  17. If the d.c's (l,m,n) of two lines are related as l + m + n = 0, 2lm -...

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  18. If the d.c's (l,m,n) of two lines are connected by the relations 3l+m+...

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  19. If the direction rations of two lines are given by 3lm-4ln+mn = 0 and ...

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  20. If the d.c's of two lines are such that l+3m+n = 0, 3l^(2) + 5m^(2) - ...

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