basic-trigonometry-angle-measure-from-cosine-sine-tangent

How to find the angle measure using a trig ratio.

Transcript

Now we are going to solve a backward problem. The reason it is a backward problem is because I will give you the ratio and you will figure out the angle measure. Let's see we will go to the second part, take the cosine of .3420 and I need to see which angle it gives me. In order to find the angle you will use your second function key wherever it might be and then cosine and you will get (cos-1 on your screen. That just means it is the inverse, and then I put in my decimal which is .342) and then close my brackets. Ok I typed it in wrong again take the second and type .3420 correctly and close brackets and I get 70.001 degrees, and I will round that to my closest whole number which is 70 degrees. That is how you work backwards.

Let's try that with sine. We are trying to find the angle A from the ratio .5150. Hit second function key, and then sine and I get sine to the negative 1, put in my decimal .5150 close brackets and I get my angle measure of 30.99. I will round this to 31 degrees which is the closest degree.

So A is 31 degrees.

Finally, we will try one with tangent. By now you should be getting the hang of it.What is the angle measure of tangent ratio .7536 Hit my second key, hit tangent, get my -1 then enter my ratio of .7536, close the bracket and I get 37 degrees. So A is 37 and that is how you work backwards to find those angles.

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Tagged under: trig,trigonometry,trig ratios,cosine,sine,tangent,moomoomath,Angle (Dimension),Trigonometric Functions,Math,math,sin,tan,hypotenuse,mathematics

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