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**+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

hectictar Mar 21, 2018

#3**+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