Expert: Paul Klarreich - 3/11/2009

Question
So the question i have is about this problem.
Find the angles of the triangle whose vertices are A(-2, 9), B(8, 8), C(8, -9). (Standard notation for triangle ABC is used throughout. Use a calculator and round off your answers to one decimal place at the end of the computation.)

i need to find the Angles of A, B, and C.

I'm not sure how to figure this out given the vertices.. can you run me through the steps..



Also this question if you have time its really important i figure this stuff out asap.. cuz i have a test on it soon..

The distance from City A to City B is 500 kilometers, that from City B to City C 855 kilometers, and that from City C to City A 980 kilometers. What are the angles in the triangle with these three cities as vertices? (Round your answers to one decimal place.)

I'm trying to find City A B and C... and i don't know how to find the angles given three sides.. could you run me though the process of getting to the answer.. thanks  

Answer
Questioner:   ray
Category:  Calculus
Private:  No
 
Subject:  cannot figure this out..
Question:  So the question i have is about this problem.
Find the angles of the triangle whose vertices are A(-2, 9), B(8, 8), C(8, -9). (Standard notation for triangle ABC is used throughout. Use a calculator and round off your answers to one decimal place at the end of the computation.)

i need to find the Angles of A, B, and C.

>> The steps are:
1. Use the distance formula to find:
 AB (which you call c)
 BC (which you call a)
 AC (which you call b)

2. Use the law of cosines to find any one of the angles.
3. Having that, you can use either the law of cosines or law of sines to find the other angles.
.............................


I'm not sure how to figure this out given the vertices.. can you run me through the steps..
............................................


Also this question if you have time its really important i figure this stuff out asap.. cuz i have a test on it soon..

The distance from City A to City B is 500 kilometers, that from City B to City C 855 kilometers, and that from City C to City A 980 kilometers. What are the angles in the triangle with these three cities as vertices? (Round your answers to one decimal place.)

I'm trying to find City A B and C... and i don't know how to find the angles given three sides.. could you run me though the process of getting to the answer.. thanks

>> this is the same thing. Any time you have three parts of a triangle which:

-- include a side and the opposite angle, use Law of Sines.

-- DO NOT include a side and the opposite angle, use Law of Cosines.