## anonymous 5 years ago I am 14 years old and I couldn't solve this trigonometry question, if tan2x=3/4 then what is the value of sinx?

1. Owlfred

Hoot! You just asked your first question! Hang tight while I find people to answer it for you. You can thank people who give you good answers by clicking the 'Good Answer' button on the right!

2. anonymous

Tan 2x = 3/4 = .75 2x = arc tan(.75) = 36.87 degrees x= 36.87/2 = 18.44 degree sinx= sin 18.44 = 0.31622 use calculator

3. anonymous

did u get the process of doing it korcan?

4. anonymous

well thanky you , but I found the answer as sinx= 1/3√5, and whats the meaning of arc?

5. anonymous

I don2T know if my answer is true.

6. anonymous

14yrs old?

7. anonymous

that makes you like yr9 , this is a yr11/12 question

8. anonymous

mark o. you did it wrong , they want an exact value for it

9. anonymous

you need to use double angle expansion

10. anonymous

YEa i am 14 years old and i learned trgionometry and function when i was 12 ^^

11. anonymous

$\tan(2x) = \frac{2\tan(x)}{1-\tan^2(x)}$

12. anonymous

mhmh just have a look at my answer mybe?

13. anonymous

14. anonymous

well u need to put the answer right awy so that we know tht u want to arrive at the answer w/c is 1/3sqrt5.....lol

15. anonymous

1/(3sqrt5) = 0.316227766 using a calculator... does your teacher allow you to use calculator? ...lol...

16. anonymous

you need to use a scientific calculator in order to solve trig, sometimes calculator serves you to check if your answer is correct....

17. anonymous

im sure you can use a table of trig fuctions?..lol

18. anonymous

arctangent is like this: tan(36.87deg)=3/4 now the reverse of it is.... 36.87deg=arc tan(3/4) or arc tan(3/4) = 36.87deg

19. anonymous

did you get it korcan?

20. anonymous

you can ask question if you are not sure so that we can explain to you better..lol

21. anonymous

OKA i got it thank you ^^but my teacher doesn2T let me use calculater, :( or table of trig fuctions :( but i know how to use it ^^

22. anonymous

and i also dun have a calculator at hause xd ^^ and dun have calculator on p ctoo but i can program a calculator when i need ^^