trig
posted by Priya on .
Find sin (alpha/2) and cos (alpha/2)
sin alpha = 3, pi/2 < alpha <less then or equal to 0
How to get the answer of sin (alpha/2) = 1/square root 3, cos(alpha/2) = square root 6/3?

You said "sin alpha = 3"
check your typing, the sine of any angle must be between ±1
Looking at your answers, α/2 is in the fourth quadrant, with x=√2, y=1, and r=√3