Question

explain cosx=1/sqrt2 = pi/4

Answer 1

see when i checked the unit circle i could not find an x that was equal to 1/square root of 2

Answer 2

the answer in the says pi/4, 7pi/4 or 3pi/4 and 5pi/4

Answer 3

i figure since cosx=x/r, i should be able to get the radians from finding an x on the unit circle that equals to 1/sqrt of 2

Answer 4

no way does \(\frac{1}{\sqrt2}=\frac{\pi}{4}\)
what you may mean is IF \(\cos(x)=\frac{1}{\sqrt2}\) THEN \(x=\frac{\pi}{4}\)

Answer 5

yes sorry

Answer 6

oooh i see the problem

Answer 7

\[\sqrt{\frac{1}{2}}=\frac{1}{\sqrt2}=\frac{\sqrt2}{2}\]

Answer 8

?? how did the last step work

Answer 9

you probably saw the third one on the unit circle and didn't recognize it as the second one

Answer 10

rationalize the denominator

Answer 11

\[\frac{1}{\sqrt2}\times \frac{\sqrt2}{\sqrt2}=\frac{\sqrt2}{2}\]

Answer 12

oh i see
how do you recognize those spots? or do you just need to have a feel for it?

Answer 13

they are all the square root of one half

Answer 14

this is the only one you will see in both forms probably

Answer 15

you will get used to it

Answer 16

ok, thank you!

Answer 17

yw

Answer 18

soryr first time using this, how do i say the question has been asnwered?

Answer 19

sorry it took a while, site crashed on me

Answer 20

you can "close' the question up top