90° is one quarter of a full turn (360°). The arc length is \(\frac{1}{4}\) of the full circumference. Remember the circumference of a circle = \(\pi d\) and the diameter = \(2 \times \text ...

90° is one quarter of the whole circle (360°). The arc length is \(\frac{1}{4}\) of the full circumference. Remember the circumference of a circle = \(\pi d\) and the diameter = \(2 \times \text ...