Trig. HW Help Please!

[alwayspositive]

Howdy everyone! I’m really not understanding this problem. I’m having a hard time setting it up... I feel like there’s not enough information to find the angles or if it’s even asking to find angles.

I’ve learned SOHCAHTOA, the Sine Rule, and the Cosine Rule. I can figure out and do any problem with them again it’s just setting up the problem and triangle.

I’ve attached a photo and if anyone could help I would appreciate it so so much!

Thank you! ?

 

[tkhunny]

You have to give us a clue where you are. Set it up by putting Point A somewhere and drawing a line segment to the north (decide which way is north). You don't need any trigonometry to find Point B. Distance = Rate * Time.

Then what?

 

[alwayspositive]

You have to give us a clue where you are. Set it up by putting Point A somewhere and drawing a line segment to the north (decide which way is north). You don't need any trigonometry to find Point B. Distance = Rate * Time.

Then what?

I understand what you mean! Am I heading in the right direction?

 

[Otis]

Hello ap. Please ensure that you complete the request to read the forum's guidelines. I like tkhunny's suggestion to start by drawing a diagram. That helps both to organize the given information and to assign symbols for unknown parts.

Three points form a triangle, yes? So we have triangle ABC in this exercise. In standard notation, we use an upper-case letter to name each vertex, and those symbols may also represent the angle measures. We then use the corresponding lower-case letter to name the side opposite a vertex, and that symbol may also represent the side's length. Here's what the diagram could look like (in my diagram, north is vertically upward):



Symbol a represents the length of the side opposite angle A
Symbol b represents the length of the side opposite angle B
Symbol c represents the length of the side opposite angle C

The first part of the exercise asks for the value of b, and the second part asks for the value of A.

As tkhunny hinted, we can use the distance formula to find the value of c and a because they've given us the starting and ending times for each segment, as well as the speed of the ship. Can you do that?

We can also find the value of B because the supplementary angle is given as 20º.

Once we have c, a, and B, we answer the questions using the Law of Cosines (for the first part) and the Law of Sines (for the second part).

Pro tip: To avoid round-off error, write down at least four decimal places, in your intermediate calculations (or use your calculator's memory to carry all digits). Do not round anything else until the very end.

Questions about any of this?

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[Otis]

… Am I heading in the right direction?

We just cross-posted! Please see my diagram in post #4.

We're told that the ship deflects 20º to the east (meaning the ship starts moving in a somewhat NNE direction), when leaving point B. Do you understand how my diagram shows that?

Also, your work (in post #3) for the distance from A to B shows that you used 1 hr for the time. That's not correct; recheck the given times for the first segment.

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