MATH CHAPTER 5: VOCABULARY

COMPLEMENTARY ANGLES

A pair of angles whose sum is 90 degrees

SUPPLEMENTARY ANGLES

A pair of angles whose sum is 180 degrees

ADJACENT ANGLES

A pair of angles that share a common vertex and common side but do not overlap.

Vertical angles

A pair of congruent angles that share a common vertex but are not adjacent. They are congruent.

Are vertical angles adjacent?

No, vertical angles are not adjacent.

Do vertical angles have the same measure?

Yes, vertical angles are congruent.

What are vertical angles formed by?

Two intersecting lines

LINEAR PAIR

A pair of supplementary adjacent angles that form a straight angle.

CONGRUENT

Having the same size and shape

CORRESPONDING ANGLES

A pair of congruent angles that are in the same relative position where two lines intersect.

ALTERNATE INTERIOR ANGLES

A pair of congruent angles that are on the inside of the parallel lines and on opposite sides of a transversal.

ALTERNATE EXTERIOR ANGLES

A pair of congruent angles that are on the outside of the parallel lines and on opposite sides of the transversal.

SAME-SIDE INTERIOR ANGLES

A pair of supplementary angles that are on the inside of the parallel lines and on the same side of the transversal.

RIGHT TRIANGLE

A triangle that has a right angle (90°)

ACUTE TRIANGLE

A triangle that has all angles less than 90° (90° is a Right Angle)

OBTUSE TRIANGLE

A triangle that has an angle greater than 90°

EQUILATERAL TRIANGLE

A triangle with all three sides of equal length. (Angle measures are the same as well)

ISOCELES TRIANGLE

A triangle with two equal sides.The angles opposite the equal sides are also equal.

SCALENE TRIANGLE

A triangle with all sides of different lengths. All angles are different, too. No sides are equal and no angles are equal.

INTERIOR ANGLES OF A TRIANGLE

Angles inside a triangle; add up to 180

EXTERIOR ANGLES OF A TRIANGLE

When the sides of a triangle are extended, the angles that are adjacent to the interior angles. The angle between any side of a shape, and a line extended from the next side.

TRIANGLE SUM THEOREM

IF 3 ANGLES FORM A TRIANGLE, THEN THEIR SUM IS 180 DEGREES

EXTERIOR ANGLE THEOREM

IN A TRIANGLE, THE MEASURE OF THE EXTERIOR ANGLES EQUALS THE SUM OF THE MEASURES OF THE TWO REMOTE INTERIOR ANGLES

TRIANGLE INEQUALITY THEOREM

The sum of the lengths of any two sides of a triangle must be GREATER THAN the length of the third side.