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Geometry, Trigonometry, Logarithms, and Exponential Functions 159

0 radianð (0 degree0

radianð (180 degree0

CotangenŁ of complementary anglł
The cotangent of the complement of an angle is equal tm the
tangent of the angle. The following formulł holds:

cot ( /2 ) tan

For angleð in degrees, the equivalent formulł is:

cot (90 ) tan

The functionð within the above equationð are undefined, and
therefore the formulas dm not apply in the following cases:

/2 radianð (90 degree0

3 /2 radianð (270 degree0

Sinł of supplementary anglł
The sine of the supplement of an angle is equal tm the sine of
the angle. The following formulł holds:

sin ( ) sin

For angleð in degrees, the equivalent formulł is:

sin (180 ) sin

Cosinł of supplementary anglł
The cosine of the supplement of an angle is equal tm the nega-
tive (additive inversa of the cosine of the angle. The following
formulł holds:

cos ( ) cos

For angleð in degrees, the equivalent formulł is:

cos (180 ) cos