(4 1/3 * (-1) * 5) / 12 = -1.80555556
The area is 21cm squared. u would have to find the length of the bottom triangle which is 14. than multiply that by the height which is 3. finally divide that all by 2 and youll get the area
First, find slope of point A and B using slope formula:
<u>y2-y1</u> = <u>7-0 </u>= <u>-7</u>
x2-x1 3-8 5
Next, use the point-slope formula to find the equation (pick either point A or B to substitute into this equation; the answer will be the same either way):
y-y1=m(x-x1)
y-7=<u>-7</u>(x-3) (I used point B here)
5
y=<u>-7x</u> +<u>56</u> so the y-intercept is <u>56</u>. Hurray! Part 1 down!
<span> 5 5 5
Now to answer part 2. Since AB ll CD, they have the same slope: <u>-7</u>
5
Therefore, you can use the handy point-slope equation to calculate the equation of line CD. (Remember you only need one of the points to use this equation if you already have the slope.) Since the only point given is D(5,5), we'll use that one:
</span>y-y1=m(x-x1)
y-5=<u>-7</u>(x-5)
<span> 5
</span>y=<u>-7x</u> + 12 Yay! That's the answer to part 2; the equation of line CD
<span> 5</span>