Answer:
The measure of ∠4 is 150°
Step-by-step explanation:
Given the figure in which BD is the diameter of circle and
m∠1=100°
m(arc BC)=∠3=30°
we have to find the measure of ∠4.
As BD is a straight line as BD is diameter therefore
∠4 and ∠3 forms a linear pair
⇒ ∠4 and ∠3 are supplementary i.e these angles adds up to 180°
∠4 + ∠3 = 180°
∠4+30°=180°
∠4=180°-30°=150°
Hence, the measure of ∠4 is 150°