Use a linear approximation of {{MATH_113}} at {{MATH_114}} to approximate {{MATH_115}}. {{CMD_116}} To start, write {{MATH_117}} so our linear approximation is {{ENV_118}} {{CMD_119}} {{COMMENT_120}} {{ENV_121}} {{COMMENT_122}} {{COMMENT_123}} {{COMMENT_124}} {{CMD_125}} Hence, a linear approximation for {{MATH_126}} at {{MATH_127}} is {{MATH_128}}, and so {{MATH_129}}. Comparing this to {{MATH_130}}, we see that the approximation is quite good. For this reason, it is common to approximate {{MATH_131}} with its linear approximation {{MATH_132}} when {{MATH_133}} is near zero. {{COMMENT_134}} {{CMD_135}} {{CMD_136}}