Question

Find the solutions 18cot2x - 6 = 0 in the interval from 0 to inclusive.

??

Answer 1

so 18. cot 2x -6 = 0

Or 18 cot 2x = 6

Now tell me if you meant cot 2x or \[\cot ^2x\]

Answer 2

Whoops, cot^2 x

Answer 3

Then its simple.

you know that cot^2x now is 6/18

i.e. cot^2x = 1/3.

You can take it from here?

Answer 4

@cmolina19 tell me this; have you studied about trigonometric ratios of standard angles like 30,60, etc?

Answer 5

well it is on this lesson. I have a table with the common first quadrant angles, but that's about it. Kind of lost though :/

Answer 6

Ok don't worry.

http://www.schooltutoring.com/help/trigonometric-ratios-of-standard-angles/

This is the table of trigonometric values of angles of 0,30,45,60,90.

Coming to your question, cot^2x = 1/3

Hence, cot x = 1/sq. root of 3 (taking sq. root of both sides)

(Refer to the table, and find out for what angle the value of cot x = 1/ sq. root of 3)

Lets say cot 20 is 1/sq. root of 3 (although its not)

Then we can say, since cot x = 1 / sq. root of 3

cot x = cot 20

Hence x = 20.

(Actually the answer is NOT 20; i want you to find the real value of x)

Answer 7

Gotcha. Thanks. :b

Answer 8

anyway the ans is 60. :P

Answer 9

yeah xD Took a while since I had to stare at the table for a while, needed my answer in radians. Shoulda specified.

Answer 10

Oh if its radians then the answer is Pi over 3 . cheers! :)