Geometry

Quadrilaterals and Polygons flashcards

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What is the sum of the interior angles of an n-sided polygon?Polygon Angle Sums
Break an n-sided polygon into triangles from one corner. There are n−2 triangles, each adding 180°.
What is the sum of the exterior angles of any convex polygon?Polygon Angle Sums
Walk once around the outside of any polygon. All your turns together make one full 360° turn.
How do you find one interior angle of a regular polygon?Polygon Angle Sums
A regular polygon shares its total angle sum equally among all its corners.
What is true about the opposite sides and angles of a parallelogram?Parallelograms
A parallelogram has two pairs of opposite sides that run in the same directions. Opposite sides and corners match.
How do the diagonals of a parallelogram behave?Parallelograms
Draw both diagonals. They cross halfway along each other, like two sticks balanced at their middles.
How can you prove a quadrilateral is a parallelogram?Parallelograms
To prove a shape is a parallelogram, show a property that forces both opposite sides to run parallel; do not judge by its sketch.
What are the key properties of a rectangle?Rectangles, Rhombi, and Squares
A rectangle has four square corners. Its two corner-to-corner diagonals are the same length.
What are the key properties of a rhombus?Rectangles, Rhombi, and Squares
A rhombus has four equal sides. Its diagonals cross at right angles.
What makes a quadrilateral a square?Rectangles, Rhombi, and Squares
A square passes both tests: four equal sides and four right angles.
Where is the midsegment of a trapezoid, and how long is it?Trapezoids and Kites
The trapezoid midsegment lies halfway between its parallel bases. Its length is the average of their lengths.
What is true about an isosceles trapezoid?Trapezoids and Kites
In an isosceles trapezoid, the nonparallel legs match, as do the corners along either base.
What are the key properties of a kite?Trapezoids and Kites
A kite has two pairs of neighboring equal sides. Its diagonals cross at a right angle, and one cuts the other in half.
How are the quadrilateral families related to each other?Classifying Quadrilaterals
Think of quadrilateral families as nested groups: every square also belongs to the rectangle, rhombus, and parallelogram groups.
How do you classify a quadrilateral on the coordinate plane?Classifying Quadrilaterals
Plot the four corners. Slopes tell which sides are parallel or perpendicular; distances tell which sides are equal.
What should you rely on when classifying a quadrilateral?Classifying Quadrilaterals
Use facts you can show—equal sides, right angles, parallel sides—not how a drawing happens to look.