Two rays meet at a point \(P\). The angle between them is \(78.4^{\circ}\). Find the size of the reflex angle at \(P\).
Question 1 Report
Two rays meet at a point \(P\). The angle between them is \(78.4^{\circ}\).
Find the size of the reflex angle at \(P\).
Answer Details
Two rays meeting at a point create two angles: the one between them and the reflex angle going the other way round. Together they make one complete turn of \(360^\circ\).
The angle between the rays is \(78.4^\circ\), so the reflex angle is
\[360-78.4=281.6^\circ\]
giving \(281.6^\circ\) [B1].
Check that the answer really is reflex: \(281.6^\circ\) lies between \(180^\circ\) and \(360^\circ\), so it qualifies. Subtracting from \(180^\circ\) instead would give \(101.6^\circ\), which is obtuse rather than reflex and so cannot be the answer to this question.
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