1. OK so if you imagine a projectile is fired with an inital velocity (u) of 400 m/s at an angle theta. What two values of theta will cause the projectile to hit a point b that is 5 km horizontally away from the point of launch and 1.5 km vertically? u (magnitude)= 400 m/s deltaH = 1500 m (1.5 km) deltaS = 5000 m (5 km) 2. constant acceleration equations, trigonometric identities. 3. What i tried to do was: ux=400cos(theta) uy=400sin(theta) using s=ut+1/2at2 1500 = 400t.Sin(theta)-4.905t2 (1) 5000 = 400t.cos(theta) t = 12.5/cos(theta) (2) substituting (2) into (1) gives, 1500 = 5000Sin(theta)/Cos(theta) - 766.4/Cos2(theta) multiplying by Cos2(theta) gives 1500cos2(theta) = 5000sin(theta)cos(theta) - 766.4 = 2500Sin(2theta) - 766.4 = 5000Cos2(theta) - 2500 - 766.4 3500cos2(theta) = 3276 cos2(theta) = 0.9361 cos(theta) = 0.9675 theta = 14.6° which is the wrong answer. Obviously i'm missing something here, but i don't know what. Hence why i'm posing the question on here. Thanks EH.