[tex]\text{Answer: }\angle DEC=60\textdegree[/tex]
Explanation:
Since we have given that
m∠BAC = 64° and m∠CBA = 56°
and AB║CD and BC║DE
First, we consider Δ ABC,
As we know two angles of a triangle so we need to find the third angle, for which we'll use the "Angle Sum Property",
Angle Sum Property, states that the sum of three angles of a triangle is [tex]180\textdegree[/tex]
Now, we will apply this,
[tex]\angle BAC+\angle ABC+\angle ACB=180\textdegree\\\\64\textdegree+56\textdegree+\angle ACB=180\textdegree\\\\120\textdegree+\angle ACB=180\textdegree\\\\\angle ACB=180\textdegree-120\textdegree\\\\\angle ACB=60\textdegree[/tex]
Now, as we have given that
BC║DE
so,
m∠ACB=m∠DEC
(∵ Corresponding angles are equal for given parallel lines)
So,
[tex]\angle ACB=\angle DEC=60\textdegree[/tex]