10.1 Point, Lines, Planes, and Angles

obtuse angle

An acute angle measures less than 90°, a right angle measures 90°, an ____________ measures more than 90° and less than 180°, and a straight angle measures 180°.

perpendicular

Lines that intersect at an angle of 90° are called ___________ lines.

transversal

Lines that lie in the same plane and have no points in common are called parallel lines. If these lines are intersected by a third line, called a __________, eight angles are formed.

true

True or False: A degree, 1°, is 1/360 of a complete rotation.

false

True or False: A ray extends infinitely in both directions.

false

True or False: A ruler is used for finding the degree measure of an angle.

false

True or False: An angle is formed by the union of two lines that have a common endpoint.

true

True or False: The measure of an angle's complement is found by subtracting the angle's measure from 90°.

true

True or False: Vertical angles have the same measure.

supplementary

Two angles whose measures have a sum of 90° are called complementary angles. Two angles whose measures have a sum of 180° are called _____________ angles.

vertical angles

When two lines intersect, the opposite angles are called __________.

ray

↔ AB symbolizes line AB, o→ AB symbolizes half-line AB, → AB symbolizes ___________ AB, and − AB line segment AB.