A radian is a unit of measurement that corresponds to the angle formed by a circle when divided into 2pi equal parts. One radian is equivalent to 57.2958 degrees. What is a radian in math? A radian is a unit of measurement for angles. One radian is equal to 180/π degrees, or approximately 57.29 degrees. What radian is equal to? One radian is defined as the angle subtended at the center of a circle by an arc that is equal in length to the radius of the circle. In other words, it is the angle between two radii of a circle that intersect at the circumference. What is a radian formula? The radian formula is a mathematical formula used to calculate the radian value of an angle. The radian formula is: radian = angle / (2 * pi). How many radians is 90? 90 radians is equal to 1.57079633 degrees. What is the radian of 2? The radian of 2 is the angle formed by two radii of a circle when the arc length between them is equal to 2. It is a unitless measurement, and is typically represented by the symbol rad.