Remember that:
[tex]\pi\text{ rad}=180^{\circ}[/tex]
Dividing both sides by 180° we get:
[tex]\frac{\pi\text{ rad}}{180^{\circ}}=1[/tex]
Which we can use as conversion factor to convert degrees to radians.
For an angle of 225°:
[tex]225^{\circ}=\frac{\pi\text{ rad}}{180^{\circ}}=\frac{225}{180}\cdot\pi\text{ rad}=\frac{5}{4}\cdot\pi\text{ rad}[/tex]
Therefore, in terms of π:
[tex]225^{\circ}=\frac{5}{4}\pi\text{ rad}[/tex]
