Head First 2D Geometry

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finding missing angles

Parallel lines are lines at exactly the same angle

Two, or more, lines which are at exactly the same angle (like the

tire tracks from the car must be) are called parallel lines. We use

little v-shaped tick marks to indicate sets of parallel lines or line

segments on a sketch.

Parallel lines can never meet or cross each other, even if you

stretch them for miles and miles and miles.…

Even if you

stretch them

forever, parallel

lines never cross

each other.

The distance between the lines

is constant—they never get

closer or farther away.

If you have more than one set of parallel lines on the same

sketch then you need to use a different number of tick marks

on each set to be able to tell them apart.

Two different sets

of parallel lines.

TIRE

TRACKS

56º

If parallel lines are always at the

same angle, and our tire tracks

are parallel, what should this

angle here be?

?º