The time taken by the projectile to reach from A to B is t. Then the distance AB is equal to

The distance AB of a projectile can be calculated using the formula for the horizontal distance (range) covered by a projectile, which is given by:

R = V₀ * t * cos(θ)

Where:

• R is the range or the horizontal distance covered (which is the distance AB in this case)
• V₀ is the initial velocity of the projectile
• t is the time taken to reach from A to B
• θ is the angle of projection

So, to calculate the distance AB, you need to know the initial velocity of the projectile, the time taken to reach from A to B, and the angle of projection.

Please note that this formula assumes that the acceleration due to gravity is constant, and that air resistance is negligible.