The bisector CD is drawn in an isosceles triangle ABC with a base AC. Find the angles of triangle ABC if ADC = 60 Degrees.
September 10, 2021 | education
| Since, by condition, the triangle ABC is isosceles, then the angle BAC = BCA.
Let the angle BAC = BCA = 2 * X0.
Since CK is the bisector of the angle BCA, then the angle BCD = ACD = BCA / 2 = X0.
The sum of the interior angles of a triangle is 180.
Then in the triangle ACD, (DAC + ACD + DKS) = 180.
(2 * X + X + 60 = 180.
3 * X = 120.
X = 120/3 = 40.
Angle BAC = BCA = 2 * 40 = 80, then angle ABC = (180 – 80 – 80) = 20.
Answer: The angles of the triangle ABC are equal to 20, 80, 80.
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