Hello!
Answer:
39°
Explanation:
- An isosceles triangle is a triangle that has two sides of equal length.
AC = AD so the triangle ACD is isoceles.
BC = AC so the triangle ABC is isoceles.
- The base angles of an isosceles triangle are equal.
ADC = 78°
So the angle ACD = 78°
- A straight angle is equal to 180°.
BCD is a straight angle, BCD = 180°.
So the angle BCA = BCD - ACD = 180° - 78° = 102°
- The sum of the angles of a triangle is equal to 180°.
The triangle ABC is isosceles.
So the angles of the base = (180° - 102°)/2 = 39°
So the angles BAC and CBA = 39°
So the value of x = 39°.