Question

A=1/2absin(theta), How is dA/dt related to d(theta)/dt and da/dt if only b is constant?
Answer: dA/dt = 1/2*ab*cos(theta)*d(theta)/dt + 1/2*b*sin(theta)*da/dt

How do i solve this

Answer 1

I will use x instead of theta.

We have A = 1/2 a b sin x.
Then dA = 1/2 ( b sin x da + a sin x db + a b cos x dx)
Therefore
dA/dt = 1/2 ( b sin x da/dt + a sin x db/dt + a b cos x dx/dt)

Answer 2

do u understand?

Answer 3

No i dont

Answer 4

That the best I can explain

Answer 5

so i set up my problem dA/dt=1/2 b d/dt [a*sin(theta)] is that right