a. | -8 or 12 | c. | 16, -8 |
b. | 6, -12 | d. | 4, |
I just did a whole page of latex and lost the whole lot so now I will do a condensed version.
Heureka, Your answer looks great but I don't understand it so I will do it my way.
Maybe you can explain your way?
Anyway here goes- again
Find the value of x such that the area of a triangle whose vertices have coordinates
P(6, 5), Q(8, 2) and R( x, 11) is 15 square units.
distance PQ=sqrt(13)
Equation of line PQ is
3x+2y-28=0
Now I need the perp distance from R to PQ
a=3, b=2, c=-28, x1=x, y1=11
$$\\d=\frac{|3x+22-28|}{\sqrt{13}}\\\\
d=\frac{|3x-6|}{\sqrt{13}}\\\\
d=\frac{|3x-6|}{\sqrt{13}}\\\\$$
$$\\\mbox{perpendicular distance from R to PQ}=\frac{|3x-6|}{\sqrt{13}}\\\\
Area=\frac{1}{2}\times \sqrt{13} \times \frac{|3x-6|}{\sqrt{13}}\\\\
15=\frac{1}{2} \times |3x-6|\\\\
30=|3x-6|\\\\
30=3x-6\qquad or \qquad 30=6-3x\\\\
36=3x\qquad\qquad or \qquad 24=-3x\\\\
x=12\qquad\qquad \;\;or \qquad x=-8\\\\$$
Below are the 2 possible triangles. :)
Find the value of x such that the area of a triangle whose vertices have coordinates (6, 5), (8, 2) and ( x, 11) is 15 square units.
$$area = \pm15 =
\dfrac{
\left|
\left[
\left(\begin{array}{c}
x\\
11
\end{array} \right)
-
\left(\begin{array}{c}
6\\
5
\end{array} \right)
\right]
\times\left[
\left(\begin{array}{c}
8\\
2
\end{array} \right)
-
\left(\begin{array}{c}
6\\
5
\end{array} \right)
\right]
\right|
}
{2}
\\\\
\pm30 =
\left|
\left[
\left(\begin{array}{c}
x\\
11
\end{array} \right)
-
\left(\begin{array}{c}
6\\
5
\end{array} \right)
\right]
\times\left[
\left(\begin{array}{c}
8\\
2
\end{array} \right)
-
\left(\begin{array}{c}
6\\
5
\end{array} \right)
\right]
\right|
} \\
\pm30 =
\left|
\left(\begin{array}{c}
x-6\\
11-5
\end{array} \right)
\times
\left(\begin{array}{c}
8-6\\
2-5
\end{array} \right)
\right|
} \\
\pm30 =
\left|
\left(\begin{array}{c}
x-6\\
6\end{array} \right)
\times
\left(\begin{array}{c}
2\\
-3\end{array} \right)
\right|
} \\\\
x_1 =?\\
30 =
\left|
\left(\begin{array}{c}
x_1-6\\
6\end{array} \right)
\times
\left(\begin{array}{c}
2\\
-3\end{array} \right)
\right|
} \\
(x_1-6)(-3)-6*2=30\\
(x_1-6)(-3)=42\\
(x_1-6)=-14\\
\textcolor[rgb]{1,0,0}{x_1 =-8}\\\\$$
$$x_2 =?\\
-30 =
\left|
\left(\begin{array}{c}
x_2-6\\
6\end{array} \right)
\times
\left(\begin{array}{c}
2\\
-3\end{array} \right)
\right|
} \\
(x_2-6)(-3)-6*2=-30\\
(x_2-6)*3+12=30\\
(x_2-6)*3=18\\
x_2-6=6\\
\textcolor[rgb]{1,0,0}{ x_2=12 }$$
a. is okay
I just did a whole page of latex and lost the whole lot so now I will do a condensed version.
Heureka, Your answer looks great but I don't understand it so I will do it my way.
Maybe you can explain your way?
Anyway here goes- again
Find the value of x such that the area of a triangle whose vertices have coordinates
P(6, 5), Q(8, 2) and R( x, 11) is 15 square units.
distance PQ=sqrt(13)
Equation of line PQ is
3x+2y-28=0
Now I need the perp distance from R to PQ
a=3, b=2, c=-28, x1=x, y1=11
$$\\d=\frac{|3x+22-28|}{\sqrt{13}}\\\\
d=\frac{|3x-6|}{\sqrt{13}}\\\\
d=\frac{|3x-6|}{\sqrt{13}}\\\\$$
$$\\\mbox{perpendicular distance from R to PQ}=\frac{|3x-6|}{\sqrt{13}}\\\\
Area=\frac{1}{2}\times \sqrt{13} \times \frac{|3x-6|}{\sqrt{13}}\\\\
15=\frac{1}{2} \times |3x-6|\\\\
30=|3x-6|\\\\
30=3x-6\qquad or \qquad 30=6-3x\\\\
36=3x\qquad\qquad or \qquad 24=-3x\\\\
x=12\qquad\qquad \;\;or \qquad x=-8\\\\$$
Below are the 2 possible triangles. :)
Melody....how did you obtain the fraction l 3x - 6 l / √13 as a perpendicular distance from R to PQ ????.....I'm not seeing how you got that
I know this formula....but I don't see how you're getting this......can you "connect the dots" more fully for me??
Thanks
I've added some more dots but if you still want more let me know. :)))
I added it in my original explanation.
Well I thought I did but it does not appear to be there.
this is not my night for presentation. LOL
I'll try again. :))
I actually recall (kinda') that method from Linear Algebra........don't remember how to calculate that cross-product......maybe I'll go back and review it....
Hey.....I'm still working out how to write an equation of a line......!!!!