Trig

posted by .

Should the triangle be solved beginning with Law of Sines of Law of Cosines. Then solve the triangle. Round to the nearest tenth. A=56 degrees, B=38 degrees, a=13.

Sines. I get confused on the formula. I know C=86 degrees

  • Trig -

    To solve a triangle you must be given 3 independent bits of information.
    2 sides and 1 angle
    3 sides
    1 side and 2 angles
    (note 3 angles is not "3 independent pieces of information, since if you know 2 angles, you automatically know the third)

    general simple rule:
    If you are given a side and its opposite angle, use the sine law
    if not, use cosine law.

    so for yours, clearly sine law.

  • Trig(I know all of that I just need to know how to use the formula) -

    I know I need to use the law of sines but I don't really know how and which one to use like sinA/a= sin B/b and sinB/b =sinC/c and sinA/a = sinC/c. That's where I get confused.

  • Trig -

    clearly you are given a side and its opposite angle, a and A, so that is obviously the ratio you are going to use

    SinA/a = SinB/b

    sin56/13 = sin38/b crossmultiply and solve for b.
    b = 13sin38/sin56
    = 9.65

    do the same to find c

  • Trig -

    b=9.7(i had to round)

    im not sure if im doing this right.

    SinB/b = SinC/c
    Sin38/9.7 = Sin86/c
    c = 9.7sin38/sin86
    c= 5.98 or 6 since I have to round to nearest tenth.

  • Trig -

    why would you not stick with the exact ration sin56/13, which uses the original numbers given

    You used an answer that you obtained after you rounded off that answer, so you are compounding your error.

  • Trig -

    so to find c all I have to do is

    Sin56/13 = Sin86/c
    c = 13Sin56/Sin86
    c = 10.8

  • Trig -

    NO

    Sin56/13 = Sin86/c now cross-multiply
    csin56 = 13sin86 divide by sin56
    c = 13sin86/sin56
    c = 15.6

    check: in any triangle, your smallest side should be across from the smallest angle, the largest side should be across the largest angle.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Trig

    Should the triangle be solved beginning with Law of Sines of Law of Cosines. Then solve the triangle. Round to the nearest tenth. a=16, b=13, c=10. Cosines A=93 degrees, B=54 degrees, C=33 degrees
  2. Trig - check my answers plz!

    1. (P -15/17, -8/17) is found on the unit circle. Find sinΘ and cosΘ Work: P= (-15/17, -8/17) cosΘ = a value P = (a,b) sinΘ = b value Answer: cosΘ = -15/17 sinΘ = -8/17 2. Should the triangle be solved …
  3. Alge2/trig

    Should the triangle be solved beginning with Laws of Sines or Laws of Cosines. Then solve the triangle and round to the nearest tenth. a=16, b=13, c=10
  4. Algebra II/ Trig

    Should the triangle be solved beginning with Laws of Sines or Laws of Cosines. Then solve the triangle and round to the nearest tenth. a=16, b=13, c=10 I got this answer but it is wrong and don't understand where I made the mistake. …
  5. math

    solve each triangle using either the Law of Sines or the Law of Cosines. If no triangle exists, write “no solution.” Round your answers to the nearest tenth. A = 23°, B = 55°, b = 9 A = 18°, a = 25, b = 18
  6. Algebra 2

    Using the information given about a triangle, which law must you use to solve the triangle?
  7. Trig - Law of sines and cosines

    ABC is an equilateral triangle with side length 4. M is the midpoint of BC, and AM is a diagonal of square ALMN. Find the area of the region common to both ABC and ALMN. I drew the diagram but I don't know how to find the answer?
  8. Trig-Medians and law of cosines and sines

    In triangle ABC, we have AB=3 and AC=4. Side BC and the median from A to BC have the same length. What is BC?
  9. Trigonometry/Geometry - Law of sines and cosines

    In most geometry courses, we learn that there's no such thing as "SSA Congruence". That is, if we have triangles ABC and DEF such that AB = DE, BC = EF, and angle A = angle D, then we cannot deduce that ABC and DEF are congruent. However, …
  10. Math

    Hello! I need help with this question. I know that I'm using the Law of Sines, but I'm confused on how to solve. I have to also round my answers to the nearest tenth for degrees and to the nearest hundredth for sides. Thanks! Given: …

More Similar Questions