Question

find the missing value. cos__=2/5
how to do this

Answer 1

Don't you use the unit circle?

Answer 2

no idea xD

Answer 3

you need to use calculator

Answer 4

\(\cos\_\_ = 2/5 \)

\(\_\_= \cos^{-1}(2/5)\)

Answer 5

ti-83 calculator xD I think any calculator can do it

Answer 6

wolfram can do it too
http://www.wolframalpha.com/input/?i=cos%5E%28-1%29%282%2F5%29

Answer 7

I got 66.42 off of my windows calculator in degree mode

Answer 8

yay I got it ! :D

Answer 9

i think solving analytically is hard
we can approximate using newton or some other numerical stuff

Answer 10

thank you
i got it