EXAMPLE \(1\) Evaluating Trigonometric Functions See LarsonPrecalculus.com for an interactive version of this type of example. Evaluate the six trigonometric functions at each real number. a. \(t = \frac { \pi } { 6 }\) b. \(t = \frac { 5 \pi } { 4 }\) c. \(t = \pi\) d. \(t = - \frac { \pi } { 3 }\)
a)
\(\sin ( 1 / 6 ^ { * } \pi ) = 0.5 = 1 / 2 \)
\( \cos ( 1 / 6 ^ { * } \pi ) = 0.8660254 = \sqrt { 3 } / 2 \)
\( \tan ( 1 / 6 ^ { * } \pi ) = 0.57735027 = 1 / \sqrt { 3 } = \sqrt { 3 } / 3 \)
\( \cot ( 1 / 6 ^ { * } \pi ) = 1.73205081 = \sqrt { 3 } \)
\( \sec ( 1 / 6 ^ { * } \pi ) = 1.15470054 = 2 \sqrt { 3 } / 3 \)
\( \csc ( 1 / 6 ^ { * } \pi ) = 2\)
b)
\(\sin ( 5 / 4 ^ { * } \pi ) = - 0.70710678 = - \sqrt { 2 } / 2 \)
\( \cos ( 5 / 4 ^ { * } \pi ) = - 0.70710678 = - \sqrt { 2 } / 2 \)
\( \tan ( 5 / 4 ^ { * } \pi ) = 1 \)
\( \cot ( 5 / 4 ^ { * } \pi ) = 1 \)
\( \sec ( 5 / 4 ^ { * } \pi ) = - 1.41421356 = - \sqrt { 2 } \)
\( \csc ( 5 / 4 ^ { * } \pi ) = - 1.41421356 = - \sqrt { 2 }\)
c)
\(\cos ( 1 ^ { * } \pi ) = - 1 \)
\( \sec ( 1 * \pi ) = - 1\)
\(\sin ( 1 ^ { * } \pi ) = 0 \)
\( \tan ( 1 ^ { * } \pi ) = 0\)
\(\cot ( 1 ^ { * } \pi ) = \) Undefined
\( C S ( 1 ^ { * } \pi ) = \) Undefined
d)
\(\sin ( - 1 / 3 ^ { * } \pi ) = - 0.8660254 = - \sqrt { 3 } / 2 \)
\( \cos ( - 1 / 3 ^ { * } \pi ) = 0.5 = 1 / 2 \)
\( \tan ( - 1 / 3 ^ { * } \pi ) = - 1.73205081 = - \sqrt { 3 } \)
\( \cot ( - 1 / 3 ^ { * } \pi ) = - 0.57735027 = - 1 / \sqrt { 3 } = - \sqrt { 3 } / 3 \)
\( \sec ( - 1 / 3 * \pi ) = 2 \)
\( \csc ( - 1 / 3 ^ { * } \pi ) = - 1.15470054 = - 2 \sqrt { 3 } / 3\)