The answers are;
- The distance between [tex](3,8)[/tex] and [tex](7,-11)[/tex] is [tex]19.42\text{ (to the nearest hundredth)}[/tex]
- The midpoint of the line [tex]JK[/tex] is [tex](6,-1)[/tex]
- The midpoint of the line [tex]AB[/tex] is [tex](8.5,9)[/tex]
- The value of [tex]y[/tex] is [tex]7[/tex]
- The slope of the line that passes through [tex](3,-6)\text{ and }(6,12)[/tex] is [tex]6[/tex]
- The value of [tex]x[/tex] is [tex]-1[/tex]
- The value of [tex]y[/tex] is [tex]-\frac{3}{2}[/tex]
- The slope of the line that passes through [tex](8,7)\text{ and }(11,7)[/tex] is [tex]0[/tex]
In coordinate geometry, given two points [tex](x_1,y_1)[/tex] and [tex](x_2,y_2)[/tex];
- The distance between them is given by [tex]d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}[/tex]
- The midpoint has the coordinates [tex](\frac{x_1+x_2}{2},\frac{y_1+y_2}{2})[/tex]
- The slope of the line passing through the points is the ratio [tex]\frac{y_2-y_1}{x_2-x_1}[/tex]
These formulae will be used to solve the following problems:
1) Given points [tex](3,8)[/tex] and [tex](7,-11)[/tex], the distance between them is
[tex]\sqrt{(7-3)^2+(-11-8)^2}\approx 19.42 \text{ (to the nearest hundredth)}[/tex]
2) If [tex]J=(-9,5) \text{ and }K=(21,-7)[/tex], the midpoint of the line [tex]JK[/tex] is
[tex](\frac{-9+21}{2}, \frac{5+(-7)}{2})=(6,-1)[/tex]
3) If [tex]A=(-8,7) \text{ and } B=(-9,11)[/tex], the midpoint of the line [tex]AB[/tex] is
[tex](\frac{-8+(-9)}{2}, \frac{7+11}{2})=(8.5,9)[/tex]
4) If the midpoint between [tex](8,y) \text{ and } (-11,6)[/tex] is [tex](-1.5,5)[/tex], then, using the
midpoint formula for the y-coordinate
[tex]6=\frac{y+5}{2} \implies y=7[/tex]
5) The slope of the line that passes through [tex](3,-6)\text{ and }(6,12)[/tex] is
[tex]\frac{12-(-6)}{6-3}=6[/tex]
6) If the slope of the line that passes through [tex](x,10)\text{ and }(-4,8)[/tex] is [tex]\frac{2}{3}[/tex], then,
using the slope formula
[tex]\frac{2}{3}=\frac{8-10}{-4-x}\\\implies \frac{2}{3}=\frac{10-8}{4+x}\\\implies \frac{2}{3}=\frac{2}{4+x}\\\implies x=-1[/tex]
7) If the slope of the line that passes through [tex](9,0)\text{ and }(3,y)[/tex] is [tex]\frac{1}{2}[/tex], then,
using the slope formula
[tex]\frac{1}{2}=\frac{y-0}{3-9}\\\implies \frac{1}{2}=\frac{y}{-3}\\\implies y=-\frac{3}{2}[/tex]
8) The slope of the line that passes through [tex](8,7)\text{ and }(11,7)[/tex] is
[tex]\frac{7-7}{11-8}=0[/tex], (since the y-coordinates of both points are equal)
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