Line integral calculus. Help!!

The path is parameterized by

so that substituting into gives

Compute the differential of :

The line integral then reduces to

To compute the integral, substitute and , so the integration domain changes to the interval .

Then substitute and . Note that in order for this substitution to be reversible, we restrict to be between -π/2 and π/2, so that the integration domain changes to .

  21.3

step-by-step explanation:

multiplying the given equation by c/sin(25°), we get

  c = 9/sin(25°) ≈ 21.2958 ≈ 21.3

we assume "c" is the length of ab, the side opposite angle c in triangle abc.