Projectile Motion problems (don't want answers to problems)

[cortb]

Homework Statement

1.A gun has a muzzle speed of 70 meters per second. Find two angles of elevation that can be used to hit an object 160 meters away.
Neglect air resistance and use g = 9.8 m / sec^{2} as the acceleration of gravity.


2.A body of mass 9 kg moves in a (counterclockwise) circular path of radius 2 meters, making one revolution every 11 seconds. You may assume the circle is in the xy-plane, and so you may ignore the third component.
A. Compute the centripetal force acting on the body.
( , )
B. Compute the magnitude of that force.


3.A ball is thrown at an angle of 45 degrees to the ground, and lands 25 meters away.
The initial speed of the ball was ... m/s

Homework Equations

The Attempt at a Solution

I am completely lost and i don't even want the actual answers, i just need to understand how i would find the answers to problems like this. is there a general formula for these types of problems?

 

[cortb]

and for the smaller angle i tried and got .16303 radians (which was wrong)... but i can't remember how i got it.