In order to evaluate {{MATH_150}}, the distance between the cyclists, at the instant when {{MATH_151}} and {{MATH_152}}, we draw a picture ``taken" at that instant. {{CMD_153}} {{ENV_154}} {{CMD_155}} By the the Pythagorean Theorem and the picture above, when {{MATH_156}}, {{MATH_157}}, it follows that {{MATH_158}} Now we can {{CMD_159}}evaluate{{CMD_160}} all the quantities in equation {{MATH_161}} and {{CMD_162}}solve{{CMD_163}} {{MATH_164}} We find that {{MATH_165}} km/hr at the moment when {{MATH_166}}, {{MATH_167}}. {{CMD_168}}