# Solving some basic trigonometry

• Nov 10th 2012, 05:15 AM
Insider
Solving some basic trigonometry
Hello all,

i am doing some project right now , but i have a small problem calculating some expressions like this :

cos(i) = cos(32) × sin(86)
so i = 32.223o

I cant understand how is this i calculated . I have stuck due to this , i know its probably something really small that i should probably know, but i am stuck now like my mind gave up -.- .

Any help is very welcome.

Those numbers (32 and 86 as well as the result i=32.223 are all in degrees)
• Nov 10th 2012, 05:20 AM
skeeter
Re: Solving some basic trigonometry
$\displaystyle i = \cos^{-1}[\cos(32) \cdot \sin(86)]$
• Nov 10th 2012, 05:35 AM
Insider
Re: Solving some basic trigonometry
Quote:

Originally Posted by skeeter
$\displaystyle i = \cos^{-1}[\cos(32) \cdot \sin(86)]$

Ah, thank you mate, that was fast, and pretty accurate.

So, using this logic , could we say that given b and c known degrees.

and sin(a)=cos(b)/cos(c) then a=asin(cos(b)/cos(c)) ? cheers.
• Nov 10th 2012, 06:19 AM
HallsofIvy
Re: Solving some basic trigonometry
Yes. Assuming that you are using a calculator, that should be fast and easy.