Question

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Answer 1

the external angle is ½ the difference of the intercepted arcs

Answer 2

85

Answer 3

or you can draw in the radius from O to C and O to B
both make 90 degree angles with the tangent lines.
the angle COB is 95 (i.e. the intercepted arc)
the angles in a shape with 4 sides add up to 360
so we have
95+90+90 + x = 360
275+x= 360
x = 360-275= 85

Answer 4

which is the same number we get using ½ the difference in intercepted arcs:
(265-95)/2 = 170/2 = 85

Answer 5

Yes okay thanks