since we know there are π radians in 180°, then how many radians are there in 153°?
[tex]\bf \begin{array}{ccll}
radians&de grees\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
\pi &180\\
x&153
\end{array}\implies \cfrac{\pi }{x}=\cfrac{180}{153}\implies \cfrac{\pi \cdot 153}{180}=x\implies \stackrel{simplified}{\cfrac{17\pi }{20}}=x[/tex]