Engrade › Wikis › Angles, Triangles, and Quadrangles

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Angles, Right Angles, Acute and Obtuse Angles

{http://s3.amazonaws.com/engrade-myfiles/4006115238733929/partsofanangle.gif} [b]Parts of an Angle[/b] The corner point of an angle is called the vertex And the two straight sides are called arms The angle is the amount of turn between each arm.

Parts of an Angle

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Types of Quadrangles (Quadrilaterals)

[http://www.mathsisfun.com/geometry/quadrilaterals-interactive.html Click here] to play with quadrilaterals online! It's fun!

Interactive Quadrilaterals

The Rectangle {http://s3.amazonaws.com/engrade-myfiles/4075021207145456/quadrilateral-rectangle.gif} means "right angle" and show equal sides A rectangle is a four-sided shape where every angle is a right angle (90°). Also opposite sides are parallel and of equal length. The Rhombus {http://s3.amazonaws.com/engrade-myfiles/4045805298955488/quadrilateral-rhombus.gif} A rhombus is a four-sided shape where all sides have equal length. Also opposite sides are parallel and opposite angles are equal. Another interesting thing is that the diagonals (dashed lines in second figure) of a rhombus bisect each other at right angles. The Square {http://s3.amazonaws.com/engrade-myfiles/4090511989588194/quadrilateral-square.gif} means "right angle" show equal sides A square has equal sides and every angle is a right angle (90°) Also opposite sides are parallel. A square also fits the definition of a rectangle (all angles are 90°), and a rhombus (all sides are equal length). The Parallelogram {http://s3.amazonaws.com/engrade-myfiles/4085682954431382/quadrilateral-parallelogram.gif} Opposite sides are parallel and equal in length, and opposite angles are equal (angles "a" are the same, and angles "b" are the same) NOTE: Squares, Rectangles and Rhombuses are all Parallelograms! Example: A parallelogram with: all sides equal and angles "a" and "b" as right angles is a square! The Trapezoid {http://s3.amazonaws.com/engrade-myfiles/4094501545195346/quadrilateral-trapezium.gif} Trapezoid Isosceles Trapezoid A trapezoid (called a trapezium in the UK) has one pair of opposite sides parallel. It is called an Isosceles trapezoid if the sides that aren't parallel are equal in length and both angles coming from a parallel side are equal, as shown. Language Note: In the US a "trapezium" is a quadrilateral with NO parallel sides! The Kite {http://s3.amazonaws.com/engrade-myfiles/4062364627247951/quadrilateral-kite.gif} Hey, it looks like a kite. It has two pairs of sides. Each pair is made up of adjacent sides that are equal in length. The angles are equal where the pairs meet. Diagonals (dashed lines) meet at a right angle, and one of the diagonal bisects (cuts equally in half) the other. ... and that's it for the special quadrilaterals.

Quadrilaterals