Coordinates Flashcards

All 7 cards in this deck

In a pair of coordinates $(x, y)$, what does the first number tell you?

e.g. $(3, -2)$

The $x$-coordinate — how far across (left or right) from the origin.

For $(3, -2)$: $3$ to the right.

What are the coordinates of the origin?

$(0, 0)$

True or false? The point $(4, -2)$ is in the same place as the point $(-2, 4)$.

False.

The order matters: $(4, -2)$ is $4$ across and $2$ down; $(-2, 4)$ is $2$ left and $4$ up.

A point lies below and to the left of the origin. What are the signs of its coordinates?

Both negative.

e.g. $(-3, -2)$

What are the steps to plot a point on a grid?

e.g. plot $(-4, 3)$

1. Start at the origin and move along the $x$-axis: $4$ to the left.
2. Then move parallel to the $y$-axis: $3$ up.
3. Mark with a cross and label it.

What are the steps to find the missing fourth vertex of a rectangle whose sides are parallel to the axes?
e.g. three vertices are $(1, 1)$, $(5, 1)$ and $(1, 4)$

1. Each $x$-coordinate should appear twice; the one appearing once is the missing $x$: from $1, 5, 1$ the missing $x = 5$.
2. Each $y$-coordinate should appear twice; the one appearing once is the missing $y$: from $1, 1, 4$ the missing $y = 4$.
3. Write the missing vertex as coordinates: $(5, 4)$.

True or false? A rectangle drawn on a coordinate grid always has its sides parallel to the axes.

False. A rectangle can be drawn tilted, so matching up repeated $x$- and $y$-coordinates only finds a missing vertex when the sides are parallel to the axes.