at a throwing speed pf 12.2 meters per seconds,what is the angle that produce a distance of 13 meters

Answer 1

under the influence of gravity?

consider the maximum height, velocity vertical is zero.

Vf=vi+gt
0=12sinTheta-9.8t
t=12sinTheta/9.8

time in the air is twice that time.

no, horizontal distance
13=12cosTheta*t=12cosTheta*2*12sinTheta/9.8

13=12^2/9.8 *2 cosTheta*sinTheta
remember siin2Theta=2sinTheta*cosTheta

solve for theta
13*9.8/144=sin 2Theta
check this.
Theta=50.6 deg