One degree in radians equals which of the following expressions?

• A. 180/pi
• B. sqrt2
• C. pi/180
• D. pi

Answer: (C)

Radians and degrees are two ways to measure angles, and they relate through the fact that 180 degrees equals π radians. Using that, 1 degree is π radians divided by 180, so 1 degree equals π/180 radians. That’s why the correct expression is π/180. The other options aren’t correct because 180/π would be the amount of degrees in one radian, not the radians in one degree; sqrt2 has no relation to angle conversion; and π would be the radians for 180 degrees, not for a single degree.