5.1k views
3 votes
Classify the triangle with the given side lengths as acute, right, obtuse, or not a triangle:

9,15,19 NOT A RIGHT TRIANGLE THANKS FOR THE HELP! NO SPAMS OR LINKS PLEASE​

2 Answers

2 votes

Answer:

acute

Explanation:

User MayaGans
by
5.7k points
4 votes

Answer:

It is not a right triangles because 15^2 + 13^2 is NOT EQUAL to 19^2

let x, y, and z be the angles inside the triangle.

Law of cosines says:

19^2 = 13^2 + 15^2 - 2(13)(15)cos x

361 = 169 + 225 - 390 cos x

-33 = -390 cos x

-33/-390 = cos x

11/130 = cos x

x = inverse cosine (11/130)

= 85.14609471338569.....

Per law of sines:

sin x/19 = sin y / 13

(13/19)sinx = sin y

inverse_sine ( (13/19) sin x) = y

y = 42.9810733896016548....

Per law of sines

sin x/19 = sin z / 15

z = inverse_sine( (15/19) sin x)

= 51.8728352950227805....

So it is an acute triangle and yes, these angles add up to 180

User Lear
by
6.7k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.