geometry question, is this true???

Question

is there 1 radiant in every 90 degrees or is it 1 radiant in every 180 degrees?
and there are 100 grads for every 90 degrees right?

Answer 1

No "t" on the end. It is radian.

Radians involve pi:
pi radians = 180 degrees.
pi/2 radians = 90 degrees
So 1 radian = 57.29578 degrees

One grad equals 9⁄10 of a degree or π⁄200 radians so yes you are right. (9/10)*100 = 90 degrees