Finding dy/dx: Differentiating (4sinx)(cosy)=1 with respect to x

[the_ace]

. differentiate (4sinx)(cosy)=1 w.r.t x and fine dy/dx


Im stuck here

(4cos x)(cos y)+ (4sin x)(-sin dy/dx[y])

 

[physicsnoob93]

Differentiating (4sinx)(cosy)=1 w.r.t. x:

4cos(x)cos(y)-4sin(x)sin(y)*dy/dx = 0 since the derivative of 1 is a constant.

is what you'll get, not whatever you wrote. you differentiate the whole function first, then multiply it with the derivative of the function inside.

Now, just solve for dy/dx.

 

[the_ace]

why its -4sin(x)sin(y)*dy...
Whts its negative 4 not PLUS!

 

[physicsnoob93]

When you differentiate cos y, you get -siny. I just brought the negative sign out.