Question

Find the exact value by using a half-angle identity.
cos (5π/12)
I have no clue how to do this....

Answer 1

the formula is cos=+or- 1+cos/2 all over a square root

Answer 2

so it will be…. 1 + cos(5pi/12)/2 all under a square root

Answer 3

@jim_thompson5910

Answer 4

@timo86m

Answer 5

that makes absolutely no sense to me...

Answer 6

@AccessDenied

Answer 7

is that the final answer?

Answer 8

no you need to solve it on you calculator

Answer 9

ehhh I have an example problem for sin and the answer isn't an exact value and there's a heck of a lot more steps

Answer 10

cos (5pi/12) = cos ((1/2)*(5pi/6))


cos (5pi/12) = sqrt( (1+cos(5pi/6))/2 )


cos (5pi/12) = sqrt( (1-sqrt(3)/2)/2 )


cos (5pi/12) = sqrt( 1/2-sqrt(3)/4 )


cos (5pi/12) = sqrt( (2-sqrt(3))/4 )


cos (5pi/12) = sqrt(1/4)*sqrt( 2-sqrt(3) )


cos (5pi/12) = (1/2)*sqrt( 2-sqrt(3) )

Answer 11

Thank you @jim_thompson5910 (:

Answer 12

yw