Answer:
m∠3 = 24°
Explanation:
By the theorem,
"Intercepted arc measures the double of the inscribed angle formed by two chords meeting at one point of the circle."
In the given picture,
∠3 is the inscribed angle subtended by the arc ED and is the intercepted arc.
Therefore, m∠3 =

m∠3 =

= 24°
Measure of angle 3 is 24 degrees.