Next, we {{CMD_198}}find equations{{CMD_199}} that combine relevant variables. In this case there are two. The first is the formula for the area of a triangle: {{MATH_200}} The second uses the fact that the larger triangle is similar to the smaller triangle, meaning that the ratios between the corresponding sides in both triangles are equal, {{MATH_201}} At this point we could {{CMD_202}}differentiate{{CMD_203}} both equations, but we choose a simpler path and express {{MATH_204}} in terms of {{MATH_205}} {{ENV_206}} Therefore, {{MATH_207}} Since {{MATH_208}} and {{MATH_209}} are both functions of time, we {{CMD_210}}differentiate{{CMD_211}} both sides of this equation with respect to {{MATH_212}} {{MATH_213}} In particular, when {{MATH_214}}, {{MATH_215}} Hence, the area is changing at a rate of {{MATH_216}} {{MATH_217}} when {{MATH_218}}m. {{CMD_219}} {{CMD_220}} {{CMD_221}}