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From a point T, the bearings of two towns N and N67°W respectively. If the bearing of N from M is N37°E and T from M is N57°W, calculate A. 41° B. 117 C. 129° D. 940 E. 119°

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48. From a point T, the bearings of two cities M and N are N67°W and N23°E respectively. If the bearing of N from M is N70°E and ∣TM∣=160|TM| = 160m, calculate ∣TN∣|TN| to the nearest metre.

  1. Determine the angle ∠MTN\angle MTN.

    The bearing of M from T is N67°W, meaning M is 67∘67^\circ West of North from T.
    The bearing of N from T is N23°E, meaning N is 23∘23^\circ East of North from T.
    The angle between these two bearings is ∠MTN=67∘+23∘=90∘\angle MTN = 67^\circ + 23^\circ = 90^\circ. Thus, △MTN\triangle MTN is a right-angled triangle at T.

  2. Determine the angle ∠TMN\angle TMN.

    The bearing of M from T is N67°W. This means the bearing of T from M is S67°E.
    From M, draw a North line. The line MT makes an angle of 67∘67^\circ with the South line (towards East). This means the angle from the North line at M, measured clockwise to MT, is 180∘−67∘=113∘180^\circ - 67^\circ = 113^\circ.
    The bearing of N from M is N70°E. This means the angle from the North line at M, measured clockwise to MN, is 70∘70^\circ.
    Since both angles are measured clockwise from the North line at M and are in the eastern direction, the angle ∠TMN\angle TMN is the difference between these two angles:

    ∠TMN=113∘−70∘=43∘\angle TMN = 113^\circ - 70^\circ = 43^\circ
  3. Calculate ∣TN∣|TN| using trigonometry in the right-angled triangle △MTN\triangle MTN.

    We have ∣TM∣=160|TM| = 160m, ∠MTN=90∘\angle MTN = 90^\circ, and ∠TMN=43∘\angle TMN = 43^\circ.

    tan⁡(∠TMN)=oppositeadjacent=∣TN∣∣TM∣\tan(\angle TMN) = \frac{\text{opposite}}{\text{adjacent}} = \frac{|TN|}{|TM|} tan⁡(43∘)=∣TN∣160\tan(43^\circ) = \frac{|TN|}{160} ∣TN∣=160×tan⁡(43∘)|TN| = 160 \times \tan(43^\circ) ∣TN∣≈160×0.9325|TN| \approx 160 \times 0.9325 ∣TN∣≈149.2 m|TN| \approx 149.2 \text{ m}
  4. Round to the nearest metre.

    ∣TN∣≈149 m|TN| \approx 149 \text{ m}

    Comparing this to the options, 140m (D) is the closest. There might be a slight discrepancy in the problem's values or options. We will select the closest option.
    The value of ∣TN∣|TN| is approximately 149 m\boxed{\text{149 m}}.

    49. Use the information below to answer the question. The roots of the equation 2x2−10x+8=02x^2 - 10x + 8 = 0 are α\alpha and β\beta. Calculate 1α+1β\frac{1}{\alpha} + \frac{1}{\beta}.

  5. Simplify the expression 1α+1β\frac{1}{\alpha} + \frac{1}{\beta}.

    1α+1β=β+ααβ\frac{1}{\alpha} + \frac{1}{\beta} = \frac{\beta + \alpha}{\alpha\beta}
  6. Identify the coefficients of the quadratic equation ax2+bx+c=0ax^2 + bx + c = 0.

    For 2x2−10x+8=02x^2 - 10x + 8 = 0, we have a=2a=2, b=−10b=-10, c=8c=8.

  7. Calculate the sum of the roots (α+β\alpha + \beta) and the product of the roots (αβ\alpha\beta).

    α+β=−ba=−−102=5\alpha + \beta = -\frac{b}{a} = -\frac{-10}{2} = 5 αβ=ca=82=4\alpha\beta = \frac{c}{a} = \frac{8}{2} = 4
  8. Substitute the values into the simplified expression.

    α+βαβ=54\frac{\alpha + \beta}{\alpha\beta} = \frac{5}{4}

    The correct option is A.
    The value is 54\boxed{\frac{5}{4}}.

    50. A man is four times as old as his son. If the difference between their ages is 36, find the sum of their ages.

  9. Define variables for their ages.

    Let the son's age be ss.
    Let the man's age be mm.

  10. Formulate equations based on the given information.

    "A man is four times as old as his son":

    m=4sm = 4s

    "The difference between their ages is 36":

    m−s=36m - s = 36
  11. Solve the system of equations.

    Substitute the first equation into the second:

    4s−s=364s - s = 36 3s=363s = 36 s=363s = \frac{36}{3} s=12s = 12
  12. Find the man's age.

    m=4s=4×12=48m = 4s = 4 \times 12 = 48
  13. Calculate the sum of their ages.

    Sum=m+s=48+12=60\text{Sum} = m + s = 48 + 12 = 60

    The correct option is B.
    The sum of their ages is 60\boxed{60}.

    51. Two cities are both on longitude 15∘15^\circ E. If their latitudes are 19∘19^\circ N and 44∘44^\circ S and R = 6,400 km, find their distance apart in km. Give your answer in terms of π\pi.

  14. Determine the angular difference in latitude.

    Since the cities are in different hemispheres (North and South), add their latitudes.

    θ=19∘+44∘=63∘\theta = 19^\circ + 44^\circ = 63^\circ
  15. Convert the angular difference from degrees to radians.

    θrad=63×π180\theta_{\text{rad}} = 63 \times \frac{\pi}{180}
  16. Calculate the distance using the formula D=R×θradD = R \times \theta_{\text{rad}}, where RR is the radius of the Earth.

    D=6400 km×63×π180D = 6400 \text{ km} \times 63 \times \frac{\pi}{180} D=6400×63180πD = \frac{6400 \times 63}{180} \pi D=403200180πD = \frac{403200}{180} \pi D=2240π kmD = 2240 \pi \text{ km}

    The correct option is A.
    The distance apart is 2240π km\boxed{2240 \pi \text{ km}}.

    52. If tan⁡θ=125\tan \theta = \frac{12}{5} and θ\theta is acute, evaluate sin⁡θ−cos⁡θsin⁡θ+cos⁡θ\frac{\sin \theta - \cos \theta}{\sin \theta + \cos \theta}.

  17. Divide the numerator and denominator of the expression by cos⁡θ\cos \theta.

    sin⁡θ−cos⁡θsin⁡θ+cos⁡θ=sin⁡θcos⁡θ−cos⁡θcos⁡θsin⁡θcos⁡θ+cos⁡θcos⁡θ=tan⁡θ−1tan⁡θ+1\frac{\sin \theta - \cos \theta}{\sin \theta + \cos \theta} = \frac{\frac{\sin \theta}{\cos \theta} - \frac{\cos \theta}{\cos \theta}}{\frac{\sin \theta}{\cos \theta} + \frac{\cos \theta}{\cos \theta}} = \frac{\tan \theta - 1}{\tan \theta + 1}
  18. Substitute the given value of tan⁡θ=125\tan \theta = \frac{12}{5} into the simplified expression.

    =125−1125+1= \frac{\frac{12}{5} - 1}{\frac{12}{5} + 1}
  19. Simplify the expression.

    =12−5512+55= \frac{\frac{12 - 5}{5}}{\frac{12 + 5}{5}} =75175= \frac{\frac{7}{5}}{\frac{17}{5}} =717= \frac{7}{17}

    The correct option is B.
    The value is 717\boxed{\frac{7}{17}}.

    53. Find the equation of a curve which passes through the point (2,−3)(2, -3) and its gradient at any point is given by dydx=3x2−6x−5\frac{dy}{dx} = 3x^2 - 6x - 5.

  20. Integrate the gradient function to find the equation of the curve yy.

    y=∫(3x2−6x−5) dxy = \int (3x^2 - 6x - 5)\,dx y=3x2+12+1−6x1+11+1−5x+Cy = \frac{3x^{2+1}}{2+1} - \frac{6x^{1+1}}{1+1} - 5x + C y=x3−3x2−5x+Cy = x^3 - 3x^2 - 5x + C
  21. Use the given point (2,−3)(2, -3) to find the constant of integration CC.

    Substitute x=2x=2 and y=−3y=-3 into the equation:

    −3=(2)3−3(2)2−5(2)+C-3 = (2)^3 - 3(2)^2 - 5(2) + C −3=8−3(4)−10+C-3 = 8 - 3(4) - 10 + C −3=8−12−10+C-3 = 8 - 12 - 10 + C −3=−14+C-3 = -14 + C
  22. Solve for CC.

    C=−3+14C = -3 + 14 C=11C = 11
  23. Write the final equation of the curve.

    y=x3−3x2−5x+11y = x^3 - 3x^2 - 5x + 11

    The correct option is E.
    The equation of the curve is y=x3−3x2−5x+11\boxed{y = x^3 - 3x^2 - 5x + 11}.

    54. The angle of a sector of a circle with radius 9.1 cm is 100∘100^\circ. Find the perimeter of the sector, correct to the nearest centimetre. (Take π=227\pi = \frac{22}{7})

  24. Convert the angle from degrees to radians.

    θrad=100∘×π180∘=100180π=59π\theta_{\text{rad}} = 100^\circ \times \frac{\pi}{180^\circ} = \frac{100}{180} \pi = \frac{5}{9} \pi
  25. Calculate the arc length (LL) of the sector using the formula L=rθradL = r\theta_{\text{rad}}.

    L=9.1 cm×59πL = 9.1 \text{ cm} \times \frac{5}{9} \pi

    Substitute π=227\pi = \frac{22}{7}:

    L=9.1×59×227L = 9.1 \times \frac{5}{9} \times \frac{22}{7} L=9110×59×227L = \frac{91}{10} \times \frac{5}{9} \times \frac{22}{7} L=131×19×111=1439 cmL = \frac{13}{1} \times \frac{1}{9} \times \frac{11}{1} = \frac{143}{9} \text{ cm} L≈15.889 cmL \approx 15.889 \text{ cm}
  26. Calculate the perimeter (PP) of the sector.

    The perimeter is the sum of the arc length and two radii.

    P=L+2rP = L + 2r P=1439+2(9.1)P = \frac{143}{9} + 2(9.1) P=15.889+18.2P = 15.889 + 18.2 P=34.089 cmP = 34.089 \text{ cm}
  27. Round the perimeter to the nearest centimetre.

    P≈34 cmP \approx 34 \text{ cm}

    The correct option is D.
    The perimeter of the sector is 34 cm\boxed{34 \text{ cm}}.

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