(81) REGULAR POLYGON

What do we call a polygon in which all angles are congruent and all sides are congruent?

(82) TRIANGLE

In what shape do all the interior angles add up to 180 degrees?

(83a) SCALENE (TRIANGLE)

What kind of triangle has no equal sides?

(83b) ISOSCELES (TRIANGLE)

What kind of triangle has two equal sides?

(83c) EQUILATERAL (TRIANGLE)

What kind of triangle has three equal sides?

(84a) ACUTE (TRIANGLE)

What do we call a triangle with all angles measuring less than 90 degrees?

(84b) OBTUSE (TRIANGLE)

What do we call a triangle containing one obtuse angle?

(84c) RIGHT (TRIANGLE)

What do we call a triangle containing one right angle?

(85) PARALLELOGRAM

What is a four-sided figure with two sets of parallel sides called?

(86) PERIMETER

What is the distance around the outside of a closed figure called?

(87) DIAMETER

What is a segment connecting two points on a circle and passing through its center called?

(88) RADIUS

What is the distance from the edge of a circle to its center called?

(89) CIRCUMFERENCE

What is the distance around a circle?

(90) C = π • d

What is the formula for finding the circumference of a circle?