Practice Questions

Q77.The position vectors of the vertices A, B and C of a triangle are 2 ^i - 3 ^j + 3 ^k, 2 ^i + 2 ^j + 3 ^k and - ^i + ^j + 3 ^k respectively. Let 𝑙 denotes the length of the angle bisector AD of ∠BAC where D is on the line segment BC, then 2𝑙2 equals : (1) 49 (2) 42 (3) 50 (4) 45

Q78.Let →a = aiˆi + a2ˆj + a3ˆk and b = b1ˆi + b2ˆj + b3ˆk be two vectors such that →a = 1;→a⋅ b = 2 and b = 4. If × −3b, then the angle between b and →cis equal to : →c= 2(→a → → → b) JEE Main 2024 (30 Jan Shift 1) JEE Main Previous Year Paper (1) cos−1( √32 ) (2) cos−1(−1√3 ) 2 ) 3 (3) cos−1(−√32 ) (4) cos−1(

Q78.Let →a = ^i + ^j + ^k,→b = 2^i + 4^j −5^k and →c = x^i + 2^j + 3^k, x ∈R. If →d is the unit vector in the direction of →b + →c such that →a ⋅→d = 1, then (→a × →b) ⋅→c is equal to (1) 11 (2) 3 (3) 9 (4) 6

Q78.Let y = y(x) be the solution of the differential equation (2x loge x) dxdy + 2y = x3 loge x, x > 0 and y (e−1) = 0. Then, y(e) is equal to (1) −3e (2) −32e (3) −23e (4) −2e

Q78.If the mirror image of the point 𝑃( 3, 4, 9 ) in the line 𝑥−1 = 𝑦+ 1 = 𝑧−2 is 𝛼, 𝛽, 𝛾, then 14𝛼+ 𝛽+ 𝛾 is: 3 2 1 (1) 102 (2) 138 (3) 108 (4) 132 𝑥+ 3 𝑦−4 𝑧+ 1

Q78.If the shortest distance between the lines is √n L2 : →r = 2(1 + μ)^i + 3(1 + μ)^j + (5 + μ)^k, μ ∈R , where gcd(m, n) = 1, then the value of m + n equals (1) 390 (2) 384 (3) 377 (4) 387

Q78.If →a = ˆi + 2ˆj + ˆk, b = 3(ˆi −ˆj + ˆk) is equal to × − b →a⋅((→c → → b) −→c) (1) 32 (2) 24 (3) 20 (4) 36

Q78.Let OA→ = 2→a, OB = 6→a + 5→b and OC = 3→b, where O is the origin. If the area of the parallelogram with −−→ → adjacent sides OA and OC is 15 sq. units, then the area (in sq. units) of the quadrilateral OABC is equal to : (1) 32 (2) 40 (3) 38 (4) 35

Q78.Let →a = 2^i + α^j + ^k,→b = −^i + ^k, →c = β^j −^k, where α and β are integers and αβ = −6. Let the values of the √21 ordered pair (α, β), for which the area of the parallelogram of diagonals →a + →b and →b + →c is , be (α1, β1) 2 and (α2, β2). Then α21 + β21 −α2β2 is equal to (1) 19 (2) 17 (3) 24 (4) 21

Q78.Let →a = 2^i + 5^j −^k,→b = 2^i −2^j + 2^k and→cbe three vectors such that (→c +^i) × (→a + →b +^i) = →a × (→c +^i). If →a ⋅→c = −29, then →c ⋅(−2^i + ^j + ^k) is equal to: (1) 15 (2) 12 (3) 10 (4) 5

Q78.Let O be the origin and the position vector of A and B be 2ˆi + 2ˆj + ˆk and 2ˆi + 4ˆj + 4ˆk respectively. If the internal bisector of ∠AOB meets the line AB at C , then the length of OC is (1) 3 2 √31 (2) 32 √34 (3) 3 4 √34 (4) 23 √31

Q78.Let a unit vector which makes an angle of 60∘ with 2^i + 2^j −^k and angle 45∘ with ^i −^k be C. Then → is : C + + (−12^i 1 ^j −√23 ^k) 3√2 (1) √2 + − + 3 + 21 )^i 1 )^j + √23 )^k ^i −12 ^k (2) ( √31 ( √31 3√2 ( √31 2√2 (3) √2 ^i + + 3 3√2 1 ^j −12 ^k (4) −√23 ^i + √23 ^j + ( 21 3 )^k

Q78.If the line 2−x 3 = 4λ+13y−2 = 4 −z makes a right angle with the line x+33μ = 1−2y6 = 5−z7 , then 4λ + 9μ is equal to : (1) 4 (2) 13 (3) 5 (4) 6

Q78.Let →a = ^i + 2^j + 3^k, b = 2^i + 3^j −5^k and→c= 3^i −^j + λ^k be three vectors. Let→rbe anit vector along →b + →c. If →r ⋅→a = 3, then 3λ is equal to: (1) 21 (2) 30 (3) 25 (4) 27

Q78.Let 𝛼, 𝛽, 𝛾 be mirror image of the point 2, 3, 5 in the line 𝑥−1 = 𝑦−2 = 𝑧−3 . Then 2𝛼+ 3𝛽+ 4𝛾 is equal to 2 3 4 (1) 32 (2) 33 (3) 31 (4) 34 𝑥−1 𝑦+ 1 𝑧+ 4

Q78.The distance of the point 𝑄( 0, 2, – 2 ) form the line passing through the point 𝑃( 5, – 4, 3 ) and perpendicular to the lines →𝑟= −3 ^𝑖+ 2 ^𝑘+ 𝜆2 ^𝑖+ 3 ^𝑗+ 5 ^𝑘, 𝜆∈ℝ and →𝑟= ^𝑖−2 ^𝑗+ ^𝑘+ 𝜇− ^𝑖+ 3 ^𝑗+ 2 ^𝑘, 𝜇∈ℝ is (1) √86 (2) √20 (3) √54 (4) √74

Q79.Let (α, β, γ) be the foot of perpendicular from the point (1, 2, 3) on the line x+35 = y−12 = z+43 . then 19(α + β + γ) is equal to : (1) 102 (2) 101 (3) 99 (4) 100

Q79.Let P(x, y, z) be a point in the first octant, whose projection in the xy-plane is the point Q. Let OP = γ ; the angle between OQ and the positive x-axis be θ; and the angle between OP and the positive z-axis be ϕ, where O is the origin. Then the distance of P from the x-axis is θ cos2 ϕ (1) γ√1 −sin2 (2) ϕ cos2 θ γ√1 −sin2 θ sin2 ϕ (3) γ√1 + cos2 (4) ϕ sin2 θ γ√1 + cos2

Q79.Let the point, on the line passing through the points P(1, −2, 3) and Q(5, −4, 7), farther from the origin and at distance of 9 units from the point P, be (α, β, γ). Then α2 + β2 + γ 2 is equal to : (1) 165 (2) 160 (3) 155 (4) 150

Q79.Let 𝐿1: →𝑟= ^𝑖- ^𝑗+ 2 ^𝑘+ 𝜆 ^𝑖- ^𝑗+ 2 ^𝑘, 𝜆∈𝑅, 𝐿2: →𝑟= ^𝑗- ^𝑘+ 𝜇3 ^𝑖+ ^𝑗+ 𝑝 ^𝑘, 𝜇∈𝑅 and 𝐿3: →𝑟= 𝛿(𝑙 ^𝑖+ 𝑚 ^𝑗+ 𝑛 ^𝑘), 𝛿∈𝑅 be three lines such that 𝐿1 is perpendicular to 𝐿2 and 𝐿3 is perpendicular to both 𝐿1 and 𝐿2. Then the point which lies on 𝐿3 is (1) ( - 1, 7, 4 ) (2) ( - 1, - 7, 4 ) (3) ( 1, 7, - 4 ) (4) ( 1, - 7, 4 )

Q79.Let PQR be a triangle with R(−1, 4, 2). Suppose M(2, 1, 2) is the mid point of PQ . The distance of the centroid of ΔPQR from the point of intersection of the line x−20 = 2y = z+3−1 and x−11 = y+3−3 = z+11 is (1) 69 (2) 9 (3) √69 (4) √99

Q79.The distance, of the point (7, −2, 11) from the line x−61 = y−40 = z−83 along the line x−52 = y−1−3 = z−56 , is : (1) 12 (2) 14 (3) 18 (4) 21

Q79.Consider the line L passing through the points (1, 2, 3) and (2, 3, 5). The distance of the point ( 113 , 113 , 193 ) from the line L along the line 3x−112 = 3y−111 = 3z−192 is equal to (1) 6 (2) 5 (3) 4 (4) 3

Q79.If the shortest distance between the lines 𝑥−𝜆 = 𝑦−2 = 𝑧−1 and 𝑥−√3 = 𝑦−1 = 𝑧−2 is 1, then the sum of all −2 1 1 1 −2 1 possible values of 𝜆 is (1) 0 (2) 2√3 (3) 3√3 (4) −2√3

Q79.The shortest distance between the lines x−3 2 = y+15−7 = z−95 and x+12 = y−11 = z−9−3 is (1) 8√3 (2) 4√3 (3) 5√3 (4) 6√3