The Ambiguous Case

Key Questions

  • Answer:

    As listed below.

    Explanation:

    For those of you who need a reminder, the ambiguous case occurs when one uses the law of sines to determine missing measures of a triangle when given two sides and an angle opposite one of those angles (SSA). ... If angle A is acute, and a = h, one possible triangle exists

    1. If angle A is acute, and a < h, no such triangle exists.

    2. If angle A is acute, and a = h, one possible triangle exists.

    3. If angle A is acute, and a > b, one possible triangle exists.

    4. If angle A is acute, and h < a < b, two possible triangles exist.

    5. If angle A is obtuse, and a < b or a = b, no such triangle exists.

    6. If angle A is obtuse, and a > b, one such triangle exists.

    ![http://slideplayer.com/slide/8654091/](useruploads.socratic.org)

  • Three numbers (a,b,c) can be the lenght of three sides of a triangle if and only if each of them is greater then the difference of the other two, and less of the sum of the other two.

    I.E: (if a>b>c)

    a>b-c,
    b>a-c,
    c>a-b;

    and:

    a<b+c,
    b<a+c,
    c<a+b.

  • Answer:

    As listed below.

    Explanation:

    If the sum is over 180°, then the second angle is not valid. First we know that this triangle is a candidate for the ambiguous case since we are given two sides and an angle not in between them. We need to find the measure of angle B using the Law of Sines: If their sum is less than 180°, we know a triangle can exist.

    (http://www.softschools.com/math/calculus/the_ambiguous_case_of_the_law_of_sines/)

    To determine if there is a 2nd valid angle:

    1. See if you are given two sides and the angle not in between (SSA). This is the situation that may have 2 possible answers.

    2. Find the value of the unknown angle.

    3. Once you find the value of your angle, subtract it from 180° to find the possible second angle.

    4. Add the new angle to the original angle. If their sum is less than 180°, you have two valid answers. If the sum is over 180°, then the second angle is not valid.

    5. If already one obtuse angle given, it can not have a second set of values.

  • To solve a triangle it is necessary to know at least three elements with an only exception: if these three elements are the three angles.

    In fact if two triangles have identical the three angles, they are similar.

Questions