6.1 Angles and Their Measure/45

Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle 90^{\circ}\cdot\frac{\pi}{180^{\circ}}=\frac{\cancel{2}\cdot \cancel{5} \cdot \cancel{3}\cdot \cancel{3}}{1}\cdot\frac{\pi}{{2}\cdot \cancel{2} \cdot \cancel{5} \cdot \cancel{3} \cdot \cancel{3}}\cdot{-1} = -\frac{\pi}{2} }