Q81.The lines lx + my + n = 0, mx + ny +l = 0 and nx + ly + m = 0 (not all equal) are concurrent if
Correct answer: l + m + n = 0
EnglishRajashtan TGT 2015 TGT 2003
Q82.Projection of lines on the axes is 2, 3, 6, then what will be the length of the line:
Correct answer: 7
Q83.For every point P(x,y,z) on the xy–plane:
Correct answer: z=0
Q84.The equation of the plane passing through the point Po(–3, 0, 7) and perpendicular to the vector ˆ ˆ ˆ x 5i 2j k = + − = + − = + − = + − is
Correct answer: 5x+2y–z+22= 0
Q85.The image of the point P(1,3,4) in the plane 2x–y+z+3 = 0 is:
Correct answer: (–3, 5, 2)
Q86.The plane lx+my+nz = p touches the conicoid ax2 +by2 +cz2 = 1, if:
Correct answer: 2 2 2 2 m n p a b c + + = l
Q87.Tangent planes are drawn to the conicoid ax2 +by2 +cz2 = 1 through the point (α, β, γ). The perpendicular from the origin to them generate
Correct answer: 2 2 2 2 () α +β + γ = + + x y z x y z a b c
Q88.(3, 6, –5)and (1, 2, 3)meets the plane through the three points (1, –2, 4), (3, 0, 2)and (3, 1, 4)
Correct answer: 4 8 51,, 5 5 5 − −
EnglishPGT 2002 UP PCS (Pre) 1996
Q89.The shortest distance between the two lines, one joining the points (–1,2, –3) and (–16, 6, 4) and the other line joining the points (1, –1,3) and (4,9,7) is:
Correct answer: 7
Q90.If l1, m1, n1; l2, m2, n2 be the direction cosines of two perpendicular straight lines, then:
Correct answer: l1l2+m1m2+n1n2 =0
EnglishRajasthan TGT 2016 L.T. 2018
Q91.If the lines x 2 y 3 z 4 3 4 5 − − − − − − − − − − − − = and x 1 y 2 z 3 3 4 − − − − − − − − − − − − = λ are coplanar, then λ is equal to
Correct answer: 2
EnglishRajasthan TGT 2016
Q92.The equation of the plane perpendicular to the yz-plane and passing through the points (1, –2, 4) and (3,–4,5) is
Correct answer: y+2z–6=0
EnglishRajasthan TGT 2016
Q93.The angle between the planes given by combined equation 6x2 +4y2 –10z2 +3yz+4zx–11xy=0 is equal to
Correct answer: 2/π
EnglishRajasthan TGT 2016
Q94.The x 1 y 21 z 1 2 6 3 − − + − − + − − + − − + = − line and the plane 3x+2y+2z=19
Correct answer: are parallel to each other
EnglishRajasthan TGT 2016
Q95.The straight line x y z m 0 − α − β + γ − α − β + γ − α − β + γ − α − β + γ = l is parallel to
Correct answer: x and y-axes both
EnglishRajasthan TGT 2016
Q96.The equation of plane parallel to x-axis is
Correct answer: by+cz+d=0
EnglishRajasthan TGT 2016
Q97.The shortest distance between the lines x 1 y 2 z 3 2 3 4 − − − − − − − − − − − − = and x 2 y 4 z 5 3 4 5 − − − − − − − − − − − − = is
Correct answer: 1/6
EnglishRajasthan TGT 2015 L.T. 2018 Lecturer GIC 2015
Q98.Co-ordinates of the foot of the perpendicular from the point (3, 1,11) − − to the line x y 2 z 3 2 3 4 − − = is
Correct answer: (2,5,7)
EnglishRajasthan TGT 2015
Q99.The image of the point (1,2,3) with respect to the plane 2x 6z 3y 35 0 + − + = + − + = + − + = + − + = is
Correct answer: (3,8, 9) − −
EnglishRajasthan TGT 2013
Q100.If 1 1 1,m,n l and 2 2 2,m,n l are direction cosines of the two lines inclined to each other at an angle θ, then the direction cosines of the external bisector of the angle between the lines are-
Correct answer: 1 2 1 2 1 2 m m n n,, 2sin 2sin 2sin 2 2 2 − − − θ l l