Find the average velocity of a projectile between the instants it crosses half the maximum height. It is projected with speed u at angle `theta` with the horizontal.

Explanation

To find the average velocity of a projectile between the instants it crosses half the maximum height, we can follow these steps:

### Step 1: Understand the projectile motion
A projectile is launched with an initial speed \( u \) at an angle \( \theta \) with the horizontal. The maximum height \( H \) reached by the projectile can be calculated using the formula:
\[ H = \frac{u^2 \sin^2 \theta}{2g} \]
where \( g \) is the acceleration due to gravity.
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