Which equation correctly describes the relationship between the measures of the angle and arcs formed by the intersecting secants?
m∠1=1/2(mPQ+mRS)
m∠1=1/2mRS
m∠1=mPQ−mRS
m∠1=1/2(mPQ−mRS)
m∠1=1/2(mPQ−mRS) is correct
+164 
