"The maximum x value can be calculated using formula:"
x_("max")=(v_i^2*sin 2alpha)/g
"where " x_("max")=100" "m" , "v_i="initial velocity"
alpha=45
2 alpha=2*45=90
sin 90=1
100=(v_i^2*sin 90)/(2*g)
100=v_i^2/(2.g)
2.g=v_i^2/100
"maximum height :"h_("max")=(v_i^2*sin^2 alpha)/(2g)
h_("max")=(v_i^2*sin^2 alpha)/(v_i^2/100)
h_("max")=cancel(v_i^2)*sin^2 alpha*100/cancel(v_i^2)
h_("max")=100*((sqrt 2)/2)^2=100*2/4=50 " m"
"we can write "h_("max")=1/2*g*t^2
50=1/2*9.81*t^2
100=9.81*t^2
t^2=100/(9.81)
t^2=10.19368
t=3.19 " s"
"time traveled"=2*3.19=6.38" "s