D1=25°
B3=25°
B1=30°
Step-by-step explanation:
1. O1+O2=360°(revolution)
310°+O2=360°
O2=360°-310°
=50°
O2=2D1(centre theorem)
50°=2D1
D1=25°
2. D1=B3=25°(tan chord theorem)
3. B2+B3=A=60°(tan chord theorem)
B1+B2+B3=90°(Radius perpendicular Tangent)
B1+60°=90°
B1=90°-60°
=30°