Answer:
85.1 m
Explanation:
The x and y coordinates are as follows
[tex]x=dcos\theta[/tex]
[tex]y=dsin\theta[/tex] where d is distance travelled and [tex]\theta[/tex] is the slope of landing
The horizontal distance travelled is [tex]x=vt= dcos\theta[/tex] where t is time take to travel and v is the velocity
Making t the subject, [tex]t=\frac {dcos\theta}{v}[/tex]
Also, the vertical distance [tex]y=0.5gt^{2}=dsin\theta but t= t=\frac {dcos\theta}{v}[/tex]
Therefore,
[tex]dsin\theta=0.5g(\frac {dcos\theta}{v})^{2}[/tex] and making d the subject of the formula
[tex]d=\frac {2v^{2}sin\theta}{gcos^{2}\theta}[/tex]
Substituting v for 20 m/s, [tex]\theta[/tex] for [tex]39*{o}[/tex] and g for [tex]9.81 m/s^{2}[/tex]
[tex]d=\frac {2*(20 m/s)^{2}*sin39^{o}}{9.8 m/s ^{2}cos^{2}39^{o}}[/tex]
d=85.06100825
Rounding off, d=85.1 m