1. ## Calculating trig ratio

Hi,

I hope someone can help. I am calculating cos(45 - 60) on my calculator and I get ((square root of 6 + square root of 2)/4)

The answer should actually be the following: https://www.wolframalpha.com/input/?...+-+30+degrees)

Why does my calculator produce a different answer than the answer on Wolfram Alpha? Any reasons?

Sincerely,
Olivia

2. ## Re: Calculating trig ratio

have you learned how to rationalize the denominator?

$\dfrac{1+\sqrt{3}}{2\sqrt{2}} \cdot \dfrac{\sqrt{2}}{\sqrt{2}} = \dfrac{\sqrt{2}+\sqrt{6}}{4}$

3. ## Re: Calculating trig ratio

Yup I know how to do it. It just didn't cross my mind to use it. Thanks for the reminder though

4. ## Re: Calculating trig ratio

A good way to check answers which appear different is to subtract one from the other. If you get zero, the two answers are equal. If you get something that is not zero, that's a problem.