Radians
The circumference of a circle is 2πr. Based on this we set that 2π(rad) is equivalent to 360° and one π(rad) is equivalent to 180°. A radian is about $360/{2π}$ or 57°18′ (in degrees).
Converting degrees to radians
$${α(°)×π}/{180°} =α(rad)$$
$$45°={45°×π}/180°=π/4 rad$$
Converting radians to degrees
$$απ(rad) =α× 180°$$
$$5/6 π rad = 5/6×180°=900°/6=150°$$
