θ → ( 5 , − 12 ) {\displaystyle \theta \rightarrow (5,-12)}
θ → x = 5 , y = − 12 , r = ? {\displaystyle \theta \rightarrow x=5,\,y=-12,\,r=\,?}
( 5 ) 2 + ( − 12 ) 2 = r 2 25 + 144 = r 2 169 = r 2 169 = r 2 13 = r {\displaystyle {\begin{aligned}(5)^{2}+(-12)^{2}&=r^{2}\\25+144&=r^{2}\\169&=r^{2}\\{\sqrt {169}}&={\sqrt {r^{2}}}\\13&=r\\\end{aligned}}}
