Results 1 to 4 of 4

Thread: Word problems - 2 problems - trig gr. 12 need immediate help ty!

  1. #1
    Newbie
    Joined
    Mar 2019
    From
    Canada
    Posts
    5

    Exclamation Word problems - 2 problems - trig gr. 12 need immediate help ty!

    1st: A pendulum is connected to a rope 3 m long, which is connected to a ceiling 4 m high. The angle between its widest swing and vertical hanging position is . If the pendulum swings out to its widest position in 2 seconds, model the height of the pendulum from the ground using a cosine function, considering vertical to be t = 0.


    so far, i think i got that the period is 4 and the minimum is 1. i can't find anything else. please help.


    2nd:
    Tonight a full moon is out. The percentage of moon that is visible, v, according to the number of days from now, d, is modelled by the equation .
    a) How many days is there until the new moon (no moon visible)?
    b) Including tonight, how many full moons will there be in the next 100 days?
    c) How many days will it be until there are five full moons, including tonight’s?
    d) Without using trigonometric ratios, write a simple equation that tells how many days away the next x full moons are. Why can the equation be so simple and consistent?

    Verify my work please? let me know if i'm right or wrong.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Oct 2009
    From
    Brisbane
    Posts
    1,223
    Thanks
    449

    Re: Word problems - 2 problems - trig gr. 12 need immediate help ty!

    1st: A pendulum is connected to a rope 3 m long, which is connected to a ceiling 4 m high. The angle between its widest swing and vertical hanging position is . If the pendulum swings out to its widest position in 2 seconds, model the height of the pendulum from the ground using a cosine function, considering vertical to be t = 0.


    so far, i think i got that the period is 4 and the minimum is 1. i can't find anything else. please help.

    Have you drawn a diagram Can you use right-angled triangle trig to find the highest vertical position reached by the pendulum? This will help you find the amplitude.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Mar 2019
    From
    Canada
    Posts
    5

    Re: Word problems - 2 problems - trig gr. 12 need immediate help ty!

    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member Cervesa's Avatar
    Joined
    Dec 2014
    From
    USA
    Posts
    66
    Thanks
    53

    Re: Word problems - 2 problems - trig gr. 12 need immediate help ty!

    (1) range of the pendulum's height above the ground is $1 \le h(t) \le 2.5$, where $h(0) = 1$, $h(2) = 2.5$ and $h(4) = 1$

    Model for pendulum bob height vs time graph is an inverted cosine curve, $h(t) = D - A\cos(Bt)$

    Amplitude is $A = \dfrac{2.5-1}{2} = 0.75$

    Midline is $D = \dfrac{1+2.5}{2} = 1.75$

    The period is $T=4 \implies B = \dfrac{2\pi}{T} = \dfrac{\pi}{2}$

    $h(t) = 1.75 - 0.75\cos\left(\dfrac{\pi}{2} \cdot t\right)$
    Attached Thumbnails Attached Thumbnails Word problems - 2 problems - trig gr. 12 need immediate help ty!-cosineh.jpg  
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 9
    Last Post: Nov 1st 2016, 10:29 PM
  2. Trig word problems
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: Oct 19th 2009, 06:04 PM
  3. Trig. Word problems. Please help.
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: Nov 24th 2008, 10:31 PM
  4. Trig Word Problems
    Posted in the Trigonometry Forum
    Replies: 6
    Last Post: Apr 24th 2008, 09:53 AM
  5. Trig word problems
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: Nov 6th 2005, 11:14 AM

Search Tags


/mathhelpforum @mathhelpforum