Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I cannot understand how i get a negative answer. I have a triangle with three angles and one side. To get another side $c$ I used the below calculation but got a negative answer.

Given that $\frac{c}{\sin C} = \frac{b}{\sin B}$ and the following calculation is made: $$c= \frac{10\times\sin 90}{\sin 68.47}$$ or $c= (10\times 0.894)/ -0.60123$ I get a negative answer for $c$?

share|cite|improve this question
Please have a look at my edit and tell me is it done correctly? – Babak S. Nov 28 '12 at 7:44

The 90 and 68.47 are in degrees, you need change the calculator to degree mode

The calculator is set to radians mode which is giving you those answers

share|cite|improve this answer
@david: In fact, $\sin 90$ is not equal to $0.894$ in any calculator. It is $1$. The same is true for anothe angle. – Babak S. Nov 28 '12 at 7:52
Thank you silly error – david Nov 28 '12 at 8:45

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.