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Math Help - help mi wif tis question!!

  1. #1
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    help mi wif tis question!!

    help mi wif tis question below~
    Attached Thumbnails Attached Thumbnails help mi wif tis question!!-13.jpg  
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  2. #2
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    Quote Originally Posted by xiaoz
    help mi wif tis question below~
    1) First question.

    1.i) Find QR.
    Angle QPR = 90 -75 = 15 degrees.
    By Law of Cosines,
    (QR)^2 = (72)^2 +(115)^2 -2(72)(115)cos(15deg)
    (QR)^2 = 2413.2683
    QR = 49.125 meters ----------answer.

    1.ii) Find (90 +angle PRQ) degrees. ---------bearing is measured clockwise.
    By Law of Sines,
    sin(angle PRQ) /(72) = sin(15deg) /(49.125)
    sin(angle PRQ) = [sin(15deg) /(49.125)]*(72) = 0.3793378
    angle PRQ = arcsin(0.3793378) = 22.29 degrees
    Therefore, bearing of Q from R is (90 +22.29) = 112.29 degrees -----answer.

    ----------------------

    2.) Second Question.

    2.i) Area of triangle PQR in terms of b, h and x.
    In triangle PQR, the height is 20% higher than h, so, height of this new triangle is (1.20)h = 1.2h
    Hence, area of triangle PQR = (1/2)(base)(height) = (1/2)(b+x)(1.2h)
    = (0.6)(b+x)(h) ------------answer.

    2.ii) Find x, in terms of b, if area of triangle PQR is twice that of triangle ABC.

    Area of triangle ABC = (1/2)(b)(h)
    So,
    (0.6)(b+x)(h) = 2[(1/2)(b)(h)]
    (0.6)(b+x)(h) = b(h)
    The h cancels out,
    (0.6)(b+x) = b
    (0.6)b +(0.6)x = b
    (0.6)x = b -(0.6)b = (0.4)b
    x = (0.4)b / (0.6)
    x = (2/3)b -----------answer.
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  3. #3
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    thxz.. but the ans for 1ii) is 292.3 degree.. ur ans is not the same ? why ?
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  4. #4
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    Quote Originally Posted by xiaoz
    thxz.. but the ans for 1ii) is 292.3 degree.. ur ans is not the same ? why ?
    Huh?
    I see.
    I based my bearing from the South, that is why only 90 degrees was added to 22.29 degrees.
    So the bearing really starts from the North, then go clockwise. So, North, +90deg first quadrant, +90deg 4th quadrant, +90deg 3rd quadrant, +22.29deg, equals (90+90+90+22.29) =?
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  5. #5
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    Talking

    o... kkz hahax
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