Answer:
Part 1) The measure of angle d is 65°
Part 2) The measure of angle c is 89°
Part 3) The measure of arc a is 131°
Part 4) The measure of arc b is 47°
Step-by-step explanation:
we know that
In an inscribed quadrilateral, opposite angles are supplementary
step 1
Find the measure of angle d
∠d+115°=180°
∠d=180°-115°=65°
step 2
Find the measure of angle c
∠c+91°=180°
∠c=180°-91°=89°
step 3
Find the measure of arc a
we know that
The inscribed angle measures half that of the arc comprising
115°=(1/2)[99°+arc a]
230°=[99°+arc a]
arc a=230°-99°=131°
step 4
Find the measure of arc b
we know that
The inscribed angle measures half that of the arc comprising
∠c=(1/2)[arc a+arc b]
substitute the values
89°=(1/2)[131°+arc b]
178°=[131°+arc b]
arc b=178°-131°=47°