Answer:
the m∠DEC=60°
Step-by-step explanation:
As given, information the triangle is shown in figure-1
Given:
m∠BAC = 50°
m∠CBA = 70°
we need to find m∠DEC
Since, sum of interior angles of triangle is 180°.
In triangle ABC,
m∠BAC+m∠CBA+m∠ACB=180°
50° + 70° + m∠ACB =180°
120° + m∠ACB =180°
subtract 120° from both the sides in above,
m∠ACB =180° - 120°
m∠ACB =160°
from the figure, we can see that BC║DE,
therefore
m∠DEC=m∠ACB
m∠DEC=60°
Therefore, the m∠DEC=60°
