Question

How do you find the cofunction of sin 65?

Answer 1

the CO function of SINE is....

Answer 2

any ideas what to do with that hint?

Answer 3

sin (90° – x) = cos x

Answer 4

Ahem.

Answer 5

Csc?

Answer 6

nope, not cosecant

that's the co-function to secant

Answer 7

take a look at this:
http://www.mathwords.com/c/cofunction_identities.htm

Answer 8

I don't understand, what does co function mean exactly?

Answer 9

cos 35?

Answer 10

The opposite of sin is csc

Answer 11

close, but it's cos(25)

the idea of a cofunction is that if f is some function and g(x) is the cofunction of f, then

f(x) = g(90-x)

or

g(x) = f(90-x)

Answer 12

examples

CO SINE is the CO function of SINE (combine CO and SINE to get COSINE)

So that helps you remember that cosine is the co-function of sine (or vice versa)

Answer 13

so

cos(x) = sin(90-x)

and

sin(x) = cos(90-x)

Answer 14

Like jim said, just plug 65 into the cofunction identity for sine.
sin (90 degrees- 65 degrees)= cos 25 degrees

Answer 15

other co-function pairs are

secant and cosecant

tangent and cotangent

Answer 16

Ok, so Sec 75=Csc 15?

Answer 17

thats the cofunction?

Answer 18

yep, you got it

Answer 19

yay :)

Answer 20

:) Is there away to right it in radian form? It asks for that too

Answer 21

the link i posted has the Pi form!

Answer 22

90 degrees = pi/2 radians

Answer 23

so just replace every occurrence of 90 with pi/2

Answer 24

ex:

cos(x) = sin(90 - x)

turns into

cos(x) = sin(pi/2 - x)

Answer 25

So it would be sec(pi/2-75)=?

Answer 26

There is nothing to do within the parenthesis

Answer 27

you need to convert 75 degrees to radians, otherwise it's not the same

Answer 28

5(pi)/12

Answer 29

pi/2-5(pi)/12

Answer 30

good, now just combine those fractions

Answer 31

pi/12?

Answer 32

good, you got it

Answer 33

so

sec(75) = csc(15)

becomes

sec(5pi/12) = csc(pi/12)

Answer 34

Just like that! I got it, thanks a lot :D

Answer 35

yw