○=> Correct option :
[tex]\color{plum}\tt\bold{(C) \: 120}[/tex]
Steps to derive correct option :
Given :
Measure of an angle = 15°
Measure of the second angle = 45°
Let the measure of the third angle be x.
We know that :
▪︎Sum of all angles of a triangle = 180°[angle sum property]
Which means :
[tex] =\tt 15 + 45 + x = 180[/tex]
[tex] =\tt 60 + x = 180[/tex]
[tex] =\tt x = 180 - 60[/tex]
[tex]\hookrightarrow\color{plum}\tt \: x = 120°[/tex]
Thus, the measure of the third angle = 120°
Since the sum of all these angles is equivalent to 180°[15+45+120=180] we can conclude that we have found out the correct measure of the third angle.
Therefore, the correct option is (C) 120
