The question describes a projectile launched from ground at an angle of $40$ degrees with an initial velocity of $96$ ft/s. I understand the concept of resolving this $96$ into x and y components. So, I can easily answer the questions of Max height (59.5 ft), how long will it take for the thing to hit the ground ($3.86 s$) and the range or max horizontal distance ($283.6$ ft). However, it then asks for the impact velocity. I now see how the $V_(xf)=V_(xi)$ since the $a_x=0$ and how $V_(yf)=V_(yi)$, however I don't see how this angle is $140$ degrees. I do see how the $V_f$ is negative, but I don't see how we can just arbitrarily assign $140$ degrees to make the final velocity negative. How do I mathematically show the angle is in Q2?
How do I get the impact angle?