Question

I need help understanding how to solve this

Thank you in advance

Answer 1

You can solve this using ratios. A full circle is 2π radians.
arc radians ÷ full circle radians = fraction of circle

π/2 ÷ 2π = 1/4

It's a fourth of the circumference

Answer 2

It’s 1/4 because its a 90 angle and 90/360 can be simplified to 1/4