Concurrent lines or line segments occur when 3 or more lines meet at the same point
It is formed at a vertex when two line segments meet each other
straight angle
Technically, lines are continuous, so parallelograms are actually composed of line segments. The line segments composing the sides of the parallelogram, come in two pairs in 2D space. Each pair is composed of two line segments that are parallel to each other, but do not occupy the same line. The two pares of line segments must all meet to then form a quadrilateral.
Normally none but it does have perpendicular lines that meet at right angles.
The definition of perpendicular lines also defines the angles -- perpendicular lines are two lines (or line segments) that meet at a 90 degree angle.
triangle * * * * * What? Two lines can make an angle, but how can they make a triangle?
Lines don't have endpoints, they extend indefinitely. Two line segments with a common endpoint form an angle.
intersecting lines, or line segments
When two line segments meet at a point
Tangent.
Concurrent lines or line segments occur when 3 or more lines meet at the same point
It is formed at a vertex when two line segments meet each other
You can find a vertex wherever two lines (or line segments) meet.
straight angle
A triangle
Technically, lines are continuous, so parallelograms are actually composed of line segments. The line segments composing the sides of the parallelogram, come in two pairs in 2D space. Each pair is composed of two line segments that are parallel to each other, but do not occupy the same line. The two pares of line segments must all meet to then form a quadrilateral.