Answer:
(a) 47°
Step-by-step explanation:
Inscribed angle ACE is half the measure of arc AE, so is 42°/2 = 21°. Angle ECD subtends the same arc as angle EBD, so has the same measure, 26°. Angle ACD is the sum of the angles that make it up:
∠ACD = ∠ACE +∠ECD
∠ACD = 21° +26° = 47°
