Question

Someone explain this to me!
How is cos(90) in radians a negative number?

Answer 1

cos(90 degrees) = 1

cos(90 radians) = -0.44807361612918

keep in mind that `180 degrees = pi radians` so we can use this to convert

90 radians = (90 radians) * (180 degrees/pi radians) = 90*(180/pi) = 5,156.6201561774 degrees

Answer 2

90 radians = 5,156.6201561774 degrees

then find the coterminal angle to `5,156.6201561774 degrees` that is between 0 and 360