Unit 1 part 2

Right Triangle

A right triangle (American English) or right-angled triangle (British English) is a triangle in which one angle is a right angle (that is, a 90-degree angle). The relation between the sides and angles of a right triangle is the basis for trigonometry.

Scalene Triangle

A scalene triangle is a triangle that has three unequal sides, such as those illustrated above. SEE ALSO: Acute Triangle, Equilateral Triangle, Isosceles Triangle, Obtuse Triangle, Triangle. CITE THIS AS: Weisstein, Eric W. "

Alternate Exterior Angles

Alternate Exterior Angles. When two lines are crossed by another line (called the Transversal): The pairs of angles on opposite sides of the transversal but outside the two lines are called Alternate Exterior Angles.

Alternate Interior Angles

Alternate interior angles are formed when a transversal passes through two lines. The angles that are formed on opposite sides of the transversal and inside the two lines are alternate interior angles. The theorem says that when the lines are parallel, that the alternate interior angles are equal.

Acute Angle

An acute angle ("acute" meaning "sharp") is an angle smaller than a right angle (it is less than 90 degrees and more than 0 degrees).If you choose the larger angle you. will have a Reflex Angle instead. The smaller angle is an Acute Angle, but the larger angle is a Reflex Angle.

Acute Triangle

An acute triangle is a triangle with all three angles acute (less than 90°). An obtuse triangle is one with one obtuse angle (greater than 90°) and two acute angles. Since a triangle's angles must sum to 180°, no triangle can have more than one obtuse angle.

Equiangular Triangle

An equiangular triangle is a triangle where all three interior angles are equal in measure. Because the interior angles of any triangle always add up to 180°, each angle is always a third of that, or 60°

Exterior Angle of a Triangle

An exterior angle of a triangle is equal to the sum of the opposite interior angles. For more on this see Triangle external angle theorem. If the equivalent angle is taken at each vertex, the exterior angles always add to 360° In fact, this is true for any convex polygon, not just triangles.

Remote Interior Angle

An exterior angle of a triangle, or any polygon, is formed by extending one of the sides of the triangle (or polygon). In a triangle, each exterior angle has two remote interior angles (see picture below). ... Click the purple button below to create an exterior angle.

Obtuse Angle

An obtuse angle is any angle larger than 90 degrees. In other words, if the angle formed where two line segments meet goes beyond a right angle, it's obtuse.

Obtuse Triangle

An obtuse triangle is a triangle in which one of the angles is an obtuse angle. (Obviously, only a single angle in a triangle can be obtuse or it wouldn't be a triangle.) A triangle must be either obtuse, acute, or right.

Corresponding Angles

the angles that occupy the same relative position at each intersection where a straight line crosses two others. If the two lines are parallel, the corresponding angles are equal.

Transversal

(of a line) intersecting a system of lines.

Adjacent

(of angles) having a common vertex and a common side

Perpendicular Lines

In elementary geometry, the property of being perpendicular (perpendicularity) is the relationship between two lines which meet at a right angle (90 degrees). The property extends to other related geometric objects. A line is said to be perpendicular to another line if the two lines intersect at a right angle.

Equilateral Triangle

In geometry, an equilateral triangle is a triangle in which all three sides are equal. In the familiar Euclidean geometry, equilateral triangles are also equiangular; that is, all three internal angles are also congruent to each other and are each 60°.

Isosceles Triangle

In geometry, an isosceles triangle is a triangle that has two sides of equal length. Sometimes it is specified as having two and only two sides of equal length, and sometimes as having at least two sides of equal length, the latter version thus including the equilateral triangle as a special case.

Parallel Lines

Parallel lines are two lines that are always the same distance apart and never touch. In order for two lines to be parallel, they must be drawn in the same plane, a perfectly flat surface like a wall or sheet of paper.

Interior Angle of a Triangle

Shape Sides Sum of Interior Angles Triangle 3 180°

Triangle Sum Theorem

The Triangle Sum Theorem states that the three interior angles of any triangle add up to 180 degrees.Jul 17, 2012

Triangle Exterior Angle Theorem

The exterior angle theorem is Proposition 1.16 in Euclid's Elements, which states that the measure of an exterior angle of a triangle is greater than either of the measures of the remote interior angles. This is a fundamental result in absolute geometry because its proof does not depend upon the parallel postulate.

Straight Angle

an angle of 180°.

Right Angle

an angle of 90°, as in a corner of a square or at the intersection of two perpendicular straight lines.

Vertical Angles

each of the pairs of opposite angles made by two intersecting lines.

Supplementary Angles

either of two angles whose sum is 180°.

Complementary Angles

either of two angles whose sum is 90°.