Question

find the exact value of tan(cos^-1(-12/13))

Answer 1

i just need help on where to graph the inverse cosine function

Answer 2

ok so would it be quadrant 2 because its negative?

Answer 3

Yes, very good.

Answer 4

\[\large \cos^{-1}\left(-\frac{12}{13}\right)\qquad\rightarrow\qquad \cos \theta=-\frac{12}{13}\]

We want to use this information to draw a triangle in the 2nd quadrant.

Answer 5

If you're ever not sure where to put the negative sign, remember that it shouldn't ever be placed on the hypotenuse.

Answer 6

ok ive got -12 on the x axis and 13 on the hypotenuse, so now would i just do -12^2+x^2=13^2 to find x

Answer 7

Good, yes, that sounds right.

Answer 8

ok i got x as sqrt(45) so would the answer for tangent be sort(45)/-12

Answer 9

sqrt45? hmm you should get sqrt25, check your math again :D

Answer 10

hmmm i got 45 again

Answer 11

Oh I see the problem,

Answer 12

\[\large (-12)^2+x^2=13^2\]Is not the same thing as,\[\large -12^2+x^2=13^2\]Make sure you're squaring the negative, as in the first example.

Answer 13

Or was that not the problem? :D heh

Answer 14

so if -12^2 is -124 wouldn't you add that to 169 making it 293

Answer 15

i squared the negative and still got 45

Answer 16

12^2=144
13^2=169

Answer 17

OH IM SO DUMB!!!

Answer 18

hehe it happens XD

Answer 19

i had it as 124 haha

Answer 20

so the answer would be 5/-12

Answer 21

yay good job :D

Answer 22

thank you so much