A circle is circumscribed around a quadrilateral, and the quadrilateral is ABCD, What is the value of arc ADC when angle D is 155 degrees?	Choose one:
A) 125  B) 100  C) 75  D) 50  E) 25
An inscribed angle is an angle in a circle composed of two chords with a common endpoint, that is, an angle with its vertex on the circle. In this problem, all four lettered angles are inscribed angles.   An inscribed angle necessarily opens to intersect an arc (the technical word is to subtend an arc). The Inscribed Angle Theorem said that the measure of an inscribed angle is always half the measure of the arc it intersects, or subtends.   angle D = 155 degrees   Thus,   arc ABC = 310 degrees   A whole circle has 360 degrees of arc, so arc ADC should be the rest of the circle.   arc A50C = 360 - 310= 
<gadget id="calculator">360 - 310</gadget>
<output>50</output>
50 degrees   Answer=(50)
<result>D</result>
A circle is circumscribed around a quadrilateral, and the quadrilateral is ABCD, What is the value of arc ADC when angle D is 155 degrees?