a chord intersected by a radius segment at a right-angle, gets bisected into two equal pieces, namely MO = NO and PZ = QZ.
[tex]\bf MO=NO\implies \stackrel{MO}{18}=NO\qquad \qquad NO=6x\implies \stackrel{NO}{18}=6x \\\\\\ \cfrac{18}{6}=x \implies 3=x \\\\[-0.35em] ~\dotfill\\\\ PZ=x+2\implies PZ=3+2\implies PZ=5=QZ \\\\[-0.35em] ~\dotfill\\\\ PQ=PZ+QZ\implies PQ=5+5\implies PQ=10[/tex]
