Asked by Lindsay
rewrite using radicals and rational numbers
Cos 3(pi)/8
Cos 3(pi)/8
Answers
Answered by
drwls
Let a = 3 pi/4 = 135 degrees
cos a = -(sqrt 2)/2
You want cos (a/2)= cos (3 pi/8)
Use the identity:
cos (a/2) = sqrt[(1/2)(1 + cos a)]
= sqrt[(1/2)(1 - (sqrt2/2)]
= sqrt[(1/2) -(sqrt2)/4]
cos a = -(sqrt 2)/2
You want cos (a/2)= cos (3 pi/8)
Use the identity:
cos (a/2) = sqrt[(1/2)(1 + cos a)]
= sqrt[(1/2)(1 - (sqrt2/2)]
= sqrt[(1/2) -(sqrt2)/4]
There are no AI answers yet. The ability to request AI answers is coming soon!
Submit Your Answer
We prioritize human answers over AI answers.
If you are human, and you can answer this question, please submit your answer.