Hello from MrBillDoesMath!
Answer:
80
Discussion:
Per the attachment, arc AB spans 110 degrees and arc BC spans 90 degrees (as that is the measure of the central angle subtending it). Hence arc ABC spans 110 + 90 = 200 degrees. As a circle has 360 degrees the smaller arc CA spans 360 - 200 = 160 degrees. But angle"b" is a tangent chord angle so its measure equals 1/2 the arc spanned, that is 1/2 ( 160 ) = 80 degrees
Thank you,
MrB
