Ask Me Help Desk

Ask Me Help Desk (https://www.askmehelpdesk.com/forum.php)
-   Math & Sciences (https://www.askmehelpdesk.com/forumdisplay.php?f=402)
-   -   Trig problem (https://www.askmehelpdesk.com/showthread.php?t=748933)

  • May 14, 2013, 03:04 PM
    chiane
    Trig problem
    Wooden plank is leaning against a wall. The bottom of the plank is 3 feet from the wall. Answer each of the following questions, and show your work.
    a) Find AC, the approximate length of the plank. Round to the nearest tenth of a foot.
    b) Find BC, the height off the ground where board touches the wall. Round to the nearest foot. Show work step by step
    Sketch has right angle... 49 degrees... AC is hypotenuse
  • May 14, 2013, 03:42 PM
    wallykap
    assume C is point on wall; B is at base of wall; and A is some distance away from wall.

    Using this triangle and assuming that angle A = 49 degrees, then
    tan A = BC / 3; and cos A = 3 / AC.

    Get a value for BC and AC by solving above using 49 degrees.

    you could check answers using Pythagorean theorem and 3 for third side of triangle.
  • May 14, 2013, 03:46 PM
    wallykap
    my guess without a calculator would be AC = 4.3 feet and BC = 3.1 feet; how close is my guess??
  • May 16, 2013, 02:56 AM
    chiane
    AC = 4.57 BC= 3.45 I used sin for BC instead of tan A... am I right ?
  • May 16, 2013, 04:56 PM
    wallykap
    Quote:

    Originally Posted by chiane View Post
    AC = 4.57 BC= 3.45 I used sin for BC instead of tan A ...am I right ?

    Not to be picky, but math is picky... be aware that "test" asked for answer to nearest foot / tenth of foot. I am pretty sure that your answers should be accurate. Don't be afraid to ask questions throughout life - learning is power.

  • All times are GMT -7. The time now is 03:24 AM.