Conversion to radians

Statement

Convert to radians: $135°$, $210°$, $315°$, $-45°$.

Solution

Use the formula $\alpha_{\text{rad}} = \dfrac{\pi}{180°}\cdot \alpha_{\text{gradi}}$: $135° = \frac{\pi}{180}\cdot 135 = \boxed{\frac{3\pi}{4}},\qquad 210° = \frac{\pi}{180}\cdot 210 = \boxed{\frac{7\pi}{6}},$ $315° = \frac{\pi}{180}\cdot 315 = \boxed{\frac{7\pi}{4}},\qquad -45° = \frac{\pi}{180}\cdot(-45) = \boxed{-\frac{\pi}{4}}.$

Links

Topics: Goniometry
Concepts: Angle · Radian
Skills: Calculating · Using formulae
Exercise types: Evaluating expressions