However when {{MATH_80}}, {{MATH_81}} starts to accumulate positively signed area, and hence is {{CMD_82}}{{CMD_83}}increasing{{CMD_84}}{{CMD_85}}decreasing{{CMD_86}}{{CMD_87}}. Thus {{MATH_88}} is increasing on {{MATH_89}}, decreasing on {{MATH_90}} and hence has a local minimum at {{MATH_91}}. {{CMD_92}} {{CMD_93}}