Answer:
The third angle is 128°.
Step-by-step explanation:
We need to remember that the sum of the 3 angles of a triangle is 180°, hence if we have 2 angles, the third angle is:
[tex] 180 = \alpha + \beta + \theta [/tex]
[tex] 180 = 12 + 40 + \theta [/tex]
[tex] \theta = 180 - 52 [/tex]
[tex] \theta = 128 [/tex]
Therefore, the third angle is 128°.
I hope it helps you!