1. The problem statement, all variables and given/known data A particle of mass m and initial velocity v0 is at (x,z)=(0,0) at t=0. The particle should hit the point (x1,z1). What is the angle for which the velocity is minimum? (Constant gravitational field -g in the z direction) 2. Relevant equations v0x = v0*cos(theta) v0z = v0*sin(theta) 3. The attempt at a solution I obtain my equations of motion: x(t) = t * v0*cos(theta) z(t) = t * v0*sin(theta) - (1/2) * g * t^2 I set x(t=t1) = x1 and solve for the time t1. Then I replace t1 in the equation for z(t=t1)=z1 and solve for v0. Then, I differentiate with respect of theta and set the derivative equal to zero to find a minimum. I get: 1 = 2 * (tan(theta))^2 - 2*z1*tan(theta)/x1 ----------- WRONG EDIT : 2*x1*(sin(θ))^2 - 2*z1*sin(θ)*cos(θ) = x1 I just don't know how to solve for theta here. It seems to me that I am over complicating things and that there should be an easier way of doing it. I just don't see it ;(.