Bentuk Mengubah Fungsi

\begin{equation*}
\begin{split}
\tan (x - 15)^{\text{o}} & = \cot (x + 25)^{\text{o}} \\\\
\tan (x - 15)^{\text{o}} & = \tan [90 - (x + 25)]^{\text{o}} \\\\
\tan (x - 15)^{\text{o}} & = \tan [90 - x - 25)]^{\text{o}} \\\\
\tan (x - 15)^{\text{o}} & = \tan (65 - x)^{\text{o}} \\\\
x - 15^{\text{o}} & = 65^{\text{o}} - x + k \:.\: 180^{\text{o}} \\\\
2x &  = 80^{\text{o}} + k \:.\: 180^{\text{o}} \\\\
x & = 40^{\text{o}} + k \:.\: 90^{\text{o}} \\\\
k & = -2 \rightarrow {\color {red} x = -140^{\text{o}}} \\\\
k & = -1 \rightarrow {\color {red} x = -50^{\text{o}}} \\\\
k & = 0 \rightarrow {\color {red} x = 40^{\text{o}}} \\\\
k & = 1 \rightarrow {\color {red} x = 130 ^{\text{o}}}
\end{split}
\end{equation*}

HP = \(\{-140^{\text{o}}, -50^{\text{o}}, 40^{\text{o}}, 130^{\text{o}} \}\)