+0

# Sin = Cos

0
1441
4
+83

What is X?

sin 41° = cos x

Should be one of my final questions.

I'm just awful at trig.

Mar 21, 2018

#1
+8961
+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

Mar 21, 2018
#2
+83
+1

Thank you a ton.

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

RedBlue  Mar 21, 2018
#3
+8961
+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
+111326
+2

Thanks, hectictar....

Let me add that  these angles always sum to 90°

So..all you need to solve is this :

x +  41  =  90

Mar 21, 2018