The measure of the central angle is the measure of the circumference angle.

Hi there! Hopefully this helps!

Twice.

The measure of the central angle is two times the measure of the circumference angle.

The central angle theorem states that the central angle from two chosen poinfs A and B on the circle is always twice the inscribed angle from two points.

Please see the attached picture

Draw a line from the point O to point P

OP = OA = OB = radius

<APO = a , <BPO = b

<PAO = a , < PBO = b

( isosceles triangle)

<POA = 180 - 2a

<POB = 180 - 2b

All Angles at centre O must add up to 360°

< AOB = 360 - ( 180 - 2a ) - ( 180 - 2b )

<AOB = 2a + 2b

<AOB = 2 ( a + b )

Hope this helps...

i think it is 18

step-by-step explanation: