Exterior Angles and Isosceles Triangles

Step-by-step explanation:

this is not an isoceles triangle.

anyway, we need to remember 2 things :

1. the sum of all angles in a triangle is always 180°.

2. the sum of all angles around a single point on a line is 360° (as this point wound be the center of an invisible circle). and as the line cuts this circle in half, the angles on one side of the line around this point is therefore 180°.

so, the internal angle Q is then

180 = 50 + 55 + Q

Q = 180 - 50 - 55 = 180 - 105 = 75°

the exterior angle x at Q is then

180 = Q + x = 75 + x

x = 180 - 75 = 105°