Answer:
Angle of projection from the horizontal will be

Step-by-step explanation:
We have given that range of the projectile is 10 times the height of the projectile
Let the projectile is projected with velocity u at an angle

Range of the projectile is equal to

And height of the projectile is equal to

Now according to question range is 10 times of height
So





So angle of projection from the horizontal will be
