Respuesta :

maxid
90+12=102

180 (all angles of a triangle are 180 degrees) - 102 (the other angles) =78 (missing angle)

The answer is 78.

Answer:

78°

Step-by-step explanation:

the whole measure of a triangle =180° =3angles plus together

the 1st + 2nd angle = 90°+12°=102°

the 3rd angle = 180°-102°=78°