2.80   ODE No. 80

1. Problem in Latex
2. Mathematica input
3. Maple input

$$(1-f^{\prime }(x))\cos (y(x))-f^{\prime }(x)+f(x)\sin (y(x))+y^{\prime }(x)-1=0$$ ✗ Mathematica : cpu = 23.7266 (sec), leaf count = 0 , could not solve

DSolve[-1 + f[x]*Sin[y[x]] + Cos[y[x]]*(1 - Derivative[1][f][x]) - Derivative[1][f][x] + Derivative[1][y][x] == 0, y[x], x]

✓ Maple : cpu = 1.49 (sec), leaf count = 41

$$\{y\left(x\right)=2\arctan \left(\frac{-{\mathrm{e}}^{\int f\left(x\right)\mathrm{d}x}+\int {\mathrm{e}}^{\int f\left(x\right)\mathrm{d}x}\mathrm{d}xf\left(x\right)+\mathit{\_}\mathit{C}\mathit{1}f\left(x\right)}{\mathit{\_}\mathit{C}\mathit{1}+\int {\mathrm{e}}^{\int f\left(x\right)\mathrm{d}x}\mathrm{d}x}\right)\}$$