Exterior Angle Theorem

Exterior Angle Theorem For a triangle The exterior angle d equals the angles b plus c. (d = b + c) The exterior angle d is greater than angle b and angle c. (do > bo, do > co) Proof d = b + c : a + b + c = 180° (Because the interior angles of

Irregular Polygon

Regular polygon is a polygon that has all angles equal and all sides equal. So, regular polygon has a = b = c = d = e, and ∠v = ∠w =∠x = ∠y = ∠z Definition of Irregular Polygon Irregular polygon is a polygon that does not have all sides equal and all angles

Angles of Elevation & Depression

Angles of Elevation Angle of elevation is the angle from the horizontal upward to an object. An observer’s line of sight would be above horizontal line. The angle of elevation is angle formed by a horizontal line & line of sight up to an object when the object is above the line. When you see


Definition Translation means Moving without rotating, resizing or anything else, just moving. To Translate a shape Every point of the shape must move: the same distance in the same direction. Learn More Angles Acute Angles Obtuse Angles Supplementary Angles Geometry Index

Acute Angles

An Acute Angle is less than 90° More Examples of Acute angles Which Angle? Remember to look carefully at which angle you are being asked to name. The acute angle is the small angle which is less than 90°. The larger angle you will have a Reflex Angle (more than 180° but less than 360°)

Parallelogram: Definition, Area, Perimeter, Diagonal, Types, Examples

Definition of Parallelogram Parallelogram is a two-dimensional shape that has parallel sides each other. The parallel sides are equals in length. Parallelogram is also a quadrilateral because it has four sides. The angles are same in the opposite. The sum of adjacent angles is 180° (supplementary angles). Sum of α + β = 180° Area of a Parallelogram

Obtuse Angles

An Obtuse Angle is more than 90° but less than 180° Examples More Examples of obtuse angles Which is Obtuse Angle? Remember to look carefully at which angle you are being asked to name. The obtuse angle is the smaller angle. It is more than 90° and less than 180°. The larger angle is a

Consecutive Interior Angles

Definitions When two lines are crossed by another line (Transversal), Consecutive Interior Angles are the pairs of angles on one side of the transversal, but inside the two lines. The 2 angles in purple (d and e) make one pair of consecutive interior angles, and the other 2 angles in red (c and f) make another

Square: Definition, Area, Perimeter, Diagonal, & Examples

Square is one of common things in daily life. There are many square things. They are chess board, clock, crackers, origami paper, etc.. Definition of Square Square is specific shape of rectangle. It is because square has right angles in all of the corner. But it has same length in all of the sides. Besides

Plane Geometry Examples

1. Johny walked in a garden start from point A. Then he walk to the west 14 meters to point B and he turn to the north 48 meters. The last position was named as C. If he want to go to C shortly, how far the distance? 2. Look at the figure Determine the