Answer:
Obtuse triangle sets
B. 5, 13, 19
C. 12, 14, 25
Step-by-step explanation:
The Pythagorean inequality for the sides of the triangle to be an obtuse:
[tex]a^2 + b^2 < c^2[/tex], where a, b and c are the sides of the triangle.
The other Pythagorean inequalities are:
[tex]a^2 + b^2 > c^2[/tex], for Acute triangle
[tex]a^2 + b^2 = c^2[/tex], for Right triangle
Now let's check which set of the given sets satisfy the above inequality.
Option A
4, 5, 6
Here a = 4, b = 5 and c = 6
[tex]4^2 + 5^2 < 6^2\\16 + 25 < 36\\41 < 36\\[/tex]
Which is not true.
Here [tex]a^2 + b^2 > c^2[/tex], So this is Acute triangle
Option B
5, 13, 19
Here a = 5, b = 13 and c = 19
[tex]5^2 + 13^2 < 19^2\\25 + 169 < 361\\194 < 361\\[/tex]
Which is true. This is Obtuse triangle
Option C
Here a = 12, b = 14 and c = 25
[tex]12^2 + 14^2 < 25^2\\144 + 196 < 625\\340 < 625\\[/tex]
Which is true. This is obtuse triangle.
Option D
Here a = 21, b = 72 and c = 75
[tex]21^2 + 72^2 < 75^2\\441 + 5184 < 5625\\5625 < 5625\\[/tex]
Which is not true for obtuse.
Here [tex]a^2 + b^2 = c^2[/tex], for Right triangle
So this is Right triangle.
