Right Angles With Same Vertex
An illustration showing when one straight line meets another straight line and makes the adjacent angles…
Adjacent Angles
An illustration of two angles that are adjacent. They have the same vertex and a common side between…
Straight Angle
An illustration showing a straight angle. When the sides of an angle extend in opposite directions,…
Acute Angle
An illustration showing an angle the is less than a right angle. This is an acute angle.
Obtuse And Reflex Angles
An illustration showing an angle the is greater than a right angle and less than a straight angle. This…
Acute, Obtuse, Straight, Right, And Reflex Angles
An illustration showing acute, obtuse, straight, right, and reflex angles.
Vertical Angles
Vertical angles are when two angles have the same vertex, and the sides of the one are prolongations…
Supplementary Angles
Illustration of supplementary angles. Two angles whose sum is a straight angle.
Superposition of Angles
Illustration of the superposition of two angles to compare magnitudes of the same kind.
Supplementary Angles
Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow…
Supplementary Angles
Illustration of supplementary angles. Two angles whose sum is a straight angle. This can be used tow…
Intersecting Straight Lines
Illustration of two lines intersecting at a point. This can be used to show vertical angles.
Lines Drawn to Another Line to Form Triangle
Illustration of two straight lines drawn from a point in a perpendicular to a given line, cutting off…
Perpendicular Line Drawn to a Given Line from an External Point
Illustration showing only one perpendicular can be drawn to a given line from a given external point.
Perpendicular Line Drawn To a Given Line From an External Point
Illustration showing that the perpendicular is the shortest line that can be drawn to a straight line…
Lines Drawn From the Point C to the Extremities of the Straight line AB
Illustration showing two lines CA and CB drawn from the point C to the extremities of the straight line…
Lines Drawn From the Same Point in a Perpendicular to a Given line, Cutting Off Segments
Illustration showing two straight lines drawn from the same point in a perpendicular to a given line,…
Parallel Lines Cut By A Transversal
Illustration showing that when two parallel lines are cut by a transversal, the exterior-interior angles…
Parallel Lines Cut By A Transversal
Illustration showing that when two parallel lines are cut by a transversal, the two interior angles…
Triangle With Segment Extended for Exterior Angle
Illustration showing a triangle with an exterior segment drawn to show and exterior angle. This can…
Acute Triangle
Illustration showing an acute triangle (one that has all three angles that are acute).
Equiangular Triangle
Illustration showing an equiangular triangle (one that has all three angles that are equal).
Triangle with Exterior Angles Drawn
Illustration showing a triangle with exterior angles. This can be used to show the sum of the three…
Isosceles Triangle With Interior Segment Drawn
Illustration showing an isosceles triangle with a segment inside. This can be used to show that in an…
Equal Triangles by Side Side Side
Illustration showing two equal triangles. This can be used to show that two triangles are equal if the…
Equal Right Triangles by Hypotenuse Leg
Illustration showing two equal right triangles. This can be used to show that two right triangles are…
Three Triangles Used to Compare Sides
Illustration showing three triangles. This is used to show the following theorem: If two triangles have…
Perpendicular Bisector of a Line
Illustration showing that the perpendicular bisector of a given line is the locus of points equidistant…
Angle Bisector
Illustration showing that the bisector of a given angle is the locus of points equidistant from the…
Angles With Parallel Sides
Illustration of two angles whose sides are parallel, each to each, to show they are either equal or…
Equal Parallelograms
Illustration of a two equal parallelograms. Two parallelograms are equal, if two sides and the included…
Right Triangle With One Angle Double the Other
Illustration of a right triangle with one angle the double of the other.
Proof of Equal Triangles Drawing
Illustration to show if two triangles have two sides of the one equal, respectively, to two sides of…
Incenter of Triangle
Illustration to show angle bisectors in a triangle. It is known as the incenter.
Circumcenter of Triangle
Illustration to show perpendicular bisectors in a triangle. It is known as the circumcenter.