Step-by-step explanation:
hope it will help you thank you
is the same thing here as the other triangles, the triangle below is an equilateral, the one above is an isosceles.
the <u>vertex</u> of the isosceles is 40°, so the twins angle at the <u>base</u> are (180 - 40)/2 = 70° = x each.
since the sides in the equilateral are all the same length, then 2y + 10 = x - y, but we already know what "x" is, so

Answer:
105°
Step-by-step explanation:
Measure of the third angle
= 180° - 18° - 57° (angle sum of triangle)
= 105°