Answer:
< BCA = 70
Explanation:
The complete central angle of a circle is 360 degrees. The given portion is 250 degrees.
What is left over? BOA = 360 - 250 = 110
Tangents always meet the radius at 90 degrees. Since there are two tangents <CAO = <BAO = 90 degrees.
So piecing it all together, the equation becomes
<BAO + CAO + BAO + ACB = 360
110 + 90 + 90 + <ACB = 360
290 + <ACB = 360
<ACB + 290 - 290 = 360 - 290
ACB = 70 degrees