The vertices of a quadrilateral in the coordinate plane are known. How can the perimeter of the figure be found?
A) Use the distance formula to find the length of each side, and then add the lengths.
B) Use the slope formula to find the slope of each of side, and then determine if the opposite sides are parallel.
C) Use the slope formula to find the slope of each of side, and then determine if the consecutive sides are perpendicular.
D) Use the distance formula to find the length of the sides, and then multiply two of the side lengths.

The perimeter is simply the distance around the outer edge of the figure, which is why we add up the four sides. The distance between points A and B is the same as the length of segment AB. You can use the pythagorean theorem to find the distance, but you'll need to draw in the right triangles. Effectively the distance formula is the pythagorean theorem, but using coordinate geometry.

x > 1.3

step by step:

8.5−0.9x> 9.8−1.9x

step 1: simplify both sides of the inequality.

−0.9x+8.5> −1.9x+9.8

step 2: add 1.9x to both sides.

−0.9x+8.5+1.9x> −1.9x+9.8+1.9x

1x+8.5> 9.8

step 3: subtract 8.5 from both sides.

1x+8.5−8.5> 9.8−8.5

1x> 1.3

step 4: divide both sides by 1.

1x/1 > 1.3/1