The small angle approximation is a mathematical approximation used in trigonometry. For small values of the arguments of trigonometric functions, we can use the following set of approximations:
sin(x) ≈ x;
cos(x) ≈ 1; and
tan(x) ≈ x.
You can derive these expressions using the series expansion of the functions: high order terms would result negligible for small values of x.
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