OPPOSITE RAYS: Two rays that are part of the same line and have only their endpoints in common.◦ Example: XZ and XY are opposite rays

STRAIGHT ANGLE: The figure formed byopposite rays

XY

Z

ANGLE: A figure where two rays have a common endpoint.

VERTEX: The common endpoint of an angle SIDES: The rays that make up an angle

S R

T

1

There are several ways to name the angle below.◦ Use the vertex and a point from each side

The vertex letter is always in the middle RST or TSR

◦ Use the vertex only If there is more than one angle at the vertex, then

you cannot use this method S

◦ Use a number Only useful when a number is given 1

S R

T

1

Name the angle below in four ways. Then identify its vertex and its sides.

4 Names: Vertex: Sides:

HI

G

3

GHI, IHG, H, 3H, 3

HG, HI

Name all angles having W as their vertex

By letters:

By numbers & letters:

RWS, SWT, TWU, RWT, SWU, RWU

3, 4, 5, RWT, SWU, RWU

An angle separates a plane into three parts: the INTERIOR of an angle, the EXTERIOR of an angle, and the angle itself.◦ In the figure to the right, point

W and all other points in blueare in the interior region

◦ Point V and all other points inthe beige area are in theexterior region

◦ Points X, Y, and Z are on the angle.

Tell whether each point is in the interior, exterior, or on the angle

D: E: F:

InteriorOnExterior

Assignment◦ Worksheet #3-1