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
4(x - 3) - r + 2x = 5(3x - 7) - 9x
4x - 12 - r + 2x = 15x - 35 - 9x
6x - 12 - r = 6x - 35
6x - 6x - 12 + 35 = r
23 = r <==
with ur answer : -r = -23....u would multiply both sides by -1 to make r positive....resulting in : r = 23....so u basically got the same thing I did...just didn't quite finish
Answerx could equal 1,-1,2,-2...
Step-by-step explanation: