Wolfram Alpha is solving this numercially not analytiaclly so you might as well, too.
b = @(t) 10*cosd(15)*(t+ 2*(45-10*sind(15)*t)/(10*sind(15)+sqrt(19.6*(45-10*sind(15)*t))))-40;
fzero(b,1)
ans =
1.4850
One important change here is that you have to use sind(theta) instead of sin(theta) since the angles are in degrees. Also I changed 19.62 to 19.6, otherwise the answer will disagree with Wolfram Alpha.
Best Answer