Question

How exactly do I solve this? Find the common logarithm of cos81degrees 40'.
a. 9.1612 - 10
b. 9.9954 - 10
c. 9.8388 - 10
d. 9.0046 - 10

Answer 1

common log? not common ANTIlog?

Answer 2

then it's just \[\log_{10} (\cos 81^o 40')\]right?

Answer 3

60 minutes = 1 degree

1 minute = 1/60 degrees

40 minutes = 40/60 degrees

40 minutes = 0.667 degrees

So 81degrees 40' = 81.667 degrees roughly

Answer 4

yikes this really musts be an old old book

Answer 5

must be the budget cuts

Answer 6

http://www.wolframalpha.com/input/?i=log%28cos%2880+degrees+40%27%29&a=UnitClash_*%27.*ArcMinutes.dflt--&a=UnitClash_*degrees.*AngularDegrees.dflt--&a=*FunClash.log-_*Log10.Log-

Answer 7

are you supposed to be looking up these answers in a table in the back of the book?
lawda mercy

Answer 8

would have helped if the answer is close to the options provided

Answer 9

no? let me check

Answer 10

Hmmm. I'm trying to match up the answers

Answer 11

would have helped more if i use 81 instead of 80

Answer 12

type
log(cos(81.6666667 deg)))+10=
in the google search window

Answer 13

replace 80 by 81 in wolfram

Answer 14

>.<

Answer 15

remember wolfram uses log10 for log base 10.

Answer 16

9.16

Answer 17

it uses natural log by default

Answer 18

a.

Answer 19

man this is a pain in the neck!

Answer 20

yeah,the first one

Answer 21

if +10 is needed in the end, then B is the closest

Answer 22

:/

Answer 23

i think it is a)

Answer 24

or A

Answer 25

charlie, what's the textbook you're using?

Answer 26

wolf gave me -0.8388
added 10 got 9.1612

Answer 27

whoaaa that's not what I got... -1.93....

Answer 28

i think the text is from maybe 1964 or earlier, before the invention of the hand held calculator

Answer 29

http://www.wolframalpha.com/input/?i=log%28cos%2881+degrees+40%27%29&a=UnitClash_*%27.*ArcMinutes.dflt--&a=UnitClash_*degrees.*AngularDegrees.dflt--&a=*FunClash.log-_*Log10.Log-
make sure it says "common log"

Answer 30

lol. I remember my professor showing me a table of logs from the 60's

Answer 31

where's my slide rule?

Answer 32

LOL I'm taking an online Precalculus/Trig class. THANKS SO MUCH GUYS FOR YOUR HELP. Wish I could give more than one medal

Answer 33

base of 10 is .0.83

Answer 34

-0.83

Answer 35

on line!!!! wtf

Answer 36

no medal for me please...

Answer 37

ancient history math with an online course
no irony here

Answer 38

@panlac01 YOU DESERVE ONE I'm sorry :(

Answer 39

i sent one for you

Answer 40

yeah. I was taking a hybrid class with face-to-face lecture and then hw's and test were done onine

Answer 41

Thanks!

Answer 42

charlie, my textbook is prolly what you need it's exactly the name of the course - pre cal with trig

Answer 43

Hmm if only I could reach through this laptop screen and steal that book from you haha

Answer 44

I've sent them to you, but you don't use them....

Answer 45

That page was difficult to understand!

Answer 46

http://finedrafts.com/files/Larson%20PreCal%208th/

Answer 47

O.k. thanks!

Answer 48

then you probably need intermediate algebra