The measure of DEF in the circle is 204° which is option c.
What is angle?
In geometry an angle is defined as the measure of the angle formed by the two rays or arms at a common vertex. Angles are measured in degrees using a protractor. The sum of angles on a line is equal to 180°.
How to find angle?
In the circle given ∠DEF is an inscribed angle subtended by an arc DF.
m ∠DEF=1/2 DF arc
but m∠DEF=78° (Given)
78=1/2 DF
DF=78*2
DF=156°
DF+DEF=360° (Expressed in angles and DEF shows arc)
DEF=360-DF (Expressed in angles)
DEF=360-156
DEF=204°
Hence the measure of DEF in the circle is 204°.
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