Posted by **shaili** on Monday, August 9, 2010 at 9:39am.

find exact value of cos(23pi/6)

- trig -
**Reiny**, Monday, August 9, 2010 at 9:44am
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 30-60-90 triangle ratios you should know that cos 30° = √3/2 ...... (30° = π/6 radians)

then cos 23π/6 = √3/2

- trig -
**Anonymous**, Monday, November 28, 2011 at 6:44pm
what is the exact value of tan pi o

ver two

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