Sr. No | List I | Sr. No | List II |
---|
| 2h + k | P. | 6
| length of ZW / length of XY | Q. | 6
| Area of ΔMZN / Area of ΔZMW | R. | 544
| α | S. | 215
T. | 26
U. | 103
Which of the following is the only incorrect combination?
IV – (S)
(I) – (P)
(III) – (R)
(IV) – (U)
Correct option is A. IV – (S)
I. 2r = MN = 3 + √(3² + 4²) + 4 = 12 ⇒ r = 6
Center C of circle C3 lies on y = (4/3)x
Let C(h, 4/3h)
OC = MC - OM = √12² - 3 = 3
∴ h² + (16/9)h² = 9 ⇒ 25h²/9 = 9 ⇒ h = 9/5
k = (4/3)h = 12/5
∴ 2h + k = 18/5 + 12/5 = 6
II. Equation of line ZW
C1 = C2 ⇒ 3x + 4y = 9
Length of XY = 2√(3² - (9/5)²) = 24/5
Distance of ZW from C |(3 × 9/5) + (4 × 12/5) - 9|/√(3² + 4²) = 6/5
Length of ZW = 2√(6² - (6/5)²) = 2√(264/25) = 24√6/5
∴ length of ZW / length of XY = 6
III. Area of ΔMZN = (1/2).NM.(1/2ZW) = 72/65
Area of ΔZMW = (1/2).ZW.(OM + OP) = (1/2)(24√6/5)(3 + 9/5) = 288√6/25
∴ Area of ΔMZN / Area of ΔZMW = 54
IV. Slope of tangent to C1 at M = -1; 4/3 = -3/4
∴ Equation of tangent y = mx - 3/√(1 + m²)
y = (-3/4)x - 3/√(1 + 9/16)
y = (-3/4)x - 12/5
⇒ x = (-4/3)y - 5 (i)
Tangent to x² = 4(2α)y is x = m'y + 2αm' (ii)
Compare (i) and (ii)
m' = -4/3 and 2αm' = -5
⇒ α = 15/8