this is the problem with the solution but i dont know what was done to reach the answer. please explain. how is C(y) equal to one. step by step on how ti solve please

1. Find a potential function , for F = (y cosx, 1 + sinx). Use 4 and the fundamental theorem of line integrals to evaluate , F . dr where C is a curve from (0, 5) to (7/2, 2). You may assume F is conservative. The fundamental theorem is f , F . dr - 4( B) - 9(A). A = (0, 5) B = (1/2, 2). To find 4, we start by integrating the first component of F with respect to r. p = / y cos edx = y sin x + C(y) Next, we solve for C(y) by taking the derivative of y with y and then setting it equal to the second component of F. Py sinr + C'(y) = 1 + sina Solving for C"(y) we get ('(y) = 1, so C(y) = fl dy = y. So then . = ysina + y. We can check our work by checking that Vo = (y cosa, 1 + sina). Using the fundamental theorem we get F . dr = 4(7/2, 2) - 4(0, 5) = (2 sin(7/2) + 7/2) - (5 sin(0) + 5) - -3+7/2 C