Respuesta :

Answer:

103°

Step-by-step explanation:

The angles in a triangle add up to equal 180°.

Answer:103°

solution,

here,

the first angle of triangle = 57°

the second angle of triangle = 20°

let, the third angle of triangle =x

we know that,

sum of angle of triangle=180°

57+20+x=180

77+x=180

x=180-77

therefore, x=103°

therefore, the third angle of triangle is 103°