trig
posted by shaili .
find exact value of cos(23pi/6)

did you notice that 23π/6 is π/6 short of 2π ?
so and angle of 23π/6 is coterminal with π/6
so cos(23π/6) = cos(π/6) = cos(π/6)
from the 306090 triangle ratios you should know that cos 30° = √3/2 ...... (30° = π/6 radians)
then cos 23π/6 = √3/2 
what is the exact value of tan pi o
ver two