## Alternate Interior Angles

Definition When two lines are crossed by another line (Transversal): Alternate Interior Angles are a pair of angles on the inner side of each of those 2 lines but on opposite sides of the transversal. How To remember: The angle pairs are on Alternate sides of the Transversal, and they are on the Interior of … Continue reading "Alternate Interior Angles"

## Vertical Angles

Definition Vertical Angles are the angles opposite each other when two lines cross In this case, “Vertical” means they share the same corner point (Vertex), not the usual meaning of up-down. Example a° and b° are vertical angles. Vertical Angles are Congruent Angles The interesting thing here is that vertical angles are congruent angles: a° … Continue reading "Vertical Angles"

## Lines of Symmetry of Plane Shapes

The line of symmetry is the axis or imaginary line that passes through the center of the shape or object and divides it into identical halves. How to find a shape has a Line of Symmetry ? You can find a shape has a Line of Symmetry or not by folding it When the folded … Continue reading "Lines of Symmetry of Plane Shapes"

## Reflex Angle

A Reflex Angle is more than 180° but less than 360° More Examples of Reflex Angle Which Angle? Remember to look carefully at which angle you are being asked to name. The reflex angle is the larger angle. It is more than 180° but less than 360° If you choose the smaller angle you might … Continue reading "Reflex Angle"

## Geometry

Geometry is a branch of mathematics concerned with questions of shape, size, relative position of figures, & the properties of space. A mathematician who works in the field of geometry is called a geometer. There are some general concepts that are more or less fundamental to geometry. These include the concepts of points, lines, planes, … Continue reading "Geometry"

## 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 … Continue reading "Exterior Angle Theorem"

## 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 … Continue reading "Irregular Polygon"

## 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 … Continue reading "Angles of Elevation & Depression"

## Translation

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°) … Continue reading "Acute Angles"