Answer:
x = 50°
Explanations:
Note that:
Sum of angles in a triangle = 180 degrees
Sum of angles on a straight line is 180 degrees
An Isosceles triangle has two sides and two angles equal
Since triangle BCD is an Iscosceles triangle and CB = CD, the angles facing the equal sides will also be equal
Therefore,
40 +
Let 100 + y = 180 (sum of angles on a straight line)
y = 180 - 100
y = 80
Since AC = CB
That is
Therefore:
x + x + 80 = 180 ( Sum of angles in triangle ABC)
2x + 80 = 180
2x = 180 - 80
2x = 100
x = 100/2
x = 50