In
mathematics, a
function f is
cofunction of a function
g if
f(
A) =
g(
B) whenever
A and
B are
complementary angles. This definition typically applies to
trigonometric functions.
For example, sine and cosine are cofunctions of each other (hence the "co" in "cosine"):
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The same is true of secant and cosecant and of tangent and cotangent:
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Sometimes writing a function in terms of its cofunction helps solve trigonometric equations. A simple example is the equation sinA = cosB
See also