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4
avatar+83 

What is X?

 

sin 41° = cos x 

 

Should be one of my final questions.

I'm just awful at trig.

RedBlue  Mar 21, 2018
 #1
avatar+7065 
+3

sin θ   =   cos( 90° - θ )

 

So.....

 

sin 41°   =   cos( 90° - 41° )

 

sin 41°  =  cos x      Plug in   cos( 90° - 41° )   for  sin 41°

 

cos( 90° - 41° )   =   cos x

 

cos 49°   =   cos x

 

49°   =   x       smiley

hectictar  Mar 21, 2018
 #2
avatar+83 
+1

Thank you a ton.

 

So it's basically just plugging with sin and cos?

RedBlue  Mar 21, 2018
 #3
avatar+7065 
+2

With problems like these just remember that

 

sin θ   =   cos( 90° - θ )       This is always true for any value of  θ .

 

You can always replace a   sin x   with  a   cos(90 - x)   because they are equal.

 

So in this case we replaced a   sin 41°   with a   cos( 90° - 41° )   because they are equal.

 

Also remember that...

 

cos θ   =   sin( 90° - θ )       This is also true for any value of  θ .

 

(All the "co-functions" are like this:  sine and cosine, secant and cosecant, and tangent and cotangent.)

 

This is kinda confusing, I know! It takes some getting used to!!

hectictar  Mar 21, 2018
 #4
avatar+86859 
+2

Thanks, hectictar....

 

Let me add that  these angles always sum to 90°

 

So..all you need to solve is this :

 

x +  41  =  90

 

 

 

cool cool cool

CPhill  Mar 21, 2018

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