f(x)=cos(x)

g(x)=sin(x)

g(x) = sin(x)
f(x) = cos(x)
a = IntegralBetween(g, f, 0.7853981633974483, 3.9269908169872414)
teksti3: "A=\int_{\frac{\pi}{4}}^{\frac{5\pi}{4}}{(g(x)-f(x))dx}=" + a