** Lesson's Content **

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** Lesson's Glossary **

**Altitude
Height **

**Altitude of a triangle (height)
The perpendicular segment from a vertex to the line containing the opposite side of a triangle. **

**Angle
Geometry shape formed by two rays (initial and ending sides of the angle) that share a common endpoint called the vertex. You may name an angle using the vertex, or a point in each ray and the vertex label in the center.**

**Angle bisector
A ray that is in the interior of an angle and forms two equal angles with the sides of that angle. Area
The amount of space taken up in a plane by a figure.**

**Area
The amount of space taken up in a plane by a figure.**

**Base
The side of an isosceles triangle whose endpoints are the vertices of the base angles.
Base angle
The angle opposite one of the equilateral sides in an isosceles triangle.**

**Cosine
Ratio determined by the hypotenuse in a right triangle and a side adjacent to a reference angle.**

**Equilateral triangle
A triangle whose sides are equal in length.**

**Isosceles triangle
A triangle with two sides of equal length.**

**Median
The segment connecting the vertex of an angle in a triangle to the midpoint of the side opposite it. **

**Obtuse angle
An angle whose measure is greater than 90 but less than 180 degrees**

**Obtuse triangle
A triangle with one acute angle.**

**Perpendicular bisector
The bisector of a segment perpendicular to it. **

**Polygon
It is a closed plane figure with a least three straight segments as sides.**

**Pythagorean theorem a2 + b2 = c2.
The Pythagorean theorem states that if you have a right triangle, then the square built on the hypotenuse is equal to the sum of the squares built on the other two sides. **

**Right triangle
A triangle that has a 90 degree angle.**

**Sine
Ratio of the length of the opposite side to a reference angle in a right triangle and the hypotenuse. Opposite/hypotenuse. **

**Scalene triangle
A triangle with no equilateral sides. **

**Triangle
A polygon with three sides.**

**Tangent
The ratio of the length of the opposite side of a reference angle to the adjacent side to the same angle. Opposite over adjacent.**

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