A tennis ball is lobbed from ground level and must cover a horizontal distance of 22m if it is to land just inside the opposite end of the court.? -->
<-- If the opponent is standing 4m from the baseline and he can hit any ball less than 3m high, what is the lowest maximum height the lob must reach to win the point?
<-- If the opponent is standing 4m from the baseline and he can hit any ball less than 3m high, what is the lowest maximum height the lob must reach to win the point?
1 Answer
Oct 7, 2017
Explanation:
#"choosing the origin at ground level from where the ball is"#
#"lobbed"#
#"then the zeros will be "x=0" and "x=-22#
#rArr"factors are "x" and (x+22)#
#rArrh(x)=ax(x+22)larrcolor(blue)" equation of parabola"#
#"the point the player must clear is "(-18,3)#
#"substitute into the equation to find a"#
#3=-72arArra=-1/24#
#rArrh(x)=-1/24x(x+22)#
#"the maximum height occurs at the midpoint of the zeros"#
#"when "x=(0-22)/2=-11#
#rArrh(-11)=-1/24xx-11xx11=5 1/24" metres"#
