When working on Assignment 5, Dilaany and Abishek worked together on Question 2: Use guess and check to find an anti-derivative F(x) for f(x)=sin(x) cos(x). Dilaany got F(x)=sin(x), which matched the official solution, and Abishek got F(x) = cos(2x). Both of them received full marks. The Question: Explain how this is possible. Are they both correct? You may use the following trigonometric identities: sin(2x) = 2 sin(x) cos(x) cos(2x) = cos(x) - sin (x) == 1= cos(x)+sin(x)